Photoresist composition and method for producing photoresist pattern

ABSTRACT

A photoresist composition comprising:
         a resin (A1) which has an acid-labile group;   a resin (A2) which comprises a structural unit represented by formula (I);       

     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1-C13 fluorinated saturated hydrocarbon group,
     A 1  represents a single bond, a C1-C6 alkanediyl group, or *-A 2 -X 1 -(A 3 -X 2 ) a -(A 4 ) b -, and   R 2  represents a C1-C18 hydrocarbon group; and
       an acid generator.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2014-252630 filed in JAPAN on Dec. 15, 2014,the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This disclosure relates to a photoresist composition and a method forproducing a photoresist pattern.

BACKGROUND ART

JP2014-044414A1 mentions a photoresist composition which comprises aresin having a structural unit of the following formula.

JP2007-140228A1 mentions a resin having structural units of thefollowing formulae.

SUMMARY

The invention of the disclosure relates to the followings:

<1> A photoresist composition comprising:

a resin (A1) which has an acid-labile group;

a resin (A2) which has a structural unit represented by formula (I);

wherein R¹ represents a C1-C13 fluorinated saturated hydrocarbon group,A¹ represents a single bond, a C1-C6 alkanediyl group, or*-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-, where * represents a binding site to anoxygen atom, A2, A³ and A⁴ each independently represent a C₁ to C₆alkanediyl group, X¹ and X² each independently represent —O—, —CO—O— or—O—OO—, “a” represents 0 or 1 and “b” represents 0 or 1, andR² represents a C1-C18 hydrocarbon group; and

an acid generator.

<2> The photoresist composition according to <1>, wherein the resin (A2)has the structural unit represented by formula (I) in an amount of 50%to 100% by mole of all the structural units of the resin (A2).<3> The photoresist composition according to <1> or <2>, wherein theresin (A2) consists of the structural unit represented by formula (I).<4> The photoresist composition according to any one of <1> to <3>,further containing a salt which generates an acid weaker in acidity thanan acid generated from the acid generator.<5> A process for producing a photoresist pattern having the followingsteps (1) to (5):

(1) a step of applying the photoresist composition according to any oneof <1> to <4> on a substrate,

(2) a step of forming a composition film by drying the composition,

(3) a step of exposing the composition film to radiation,

(4) a step of baking the exposed composition film, and

(5) a step of developing the baked composition film, thereby forming thephotoresist pattern.

DESCRIPTION OF PREFERRED EMBODIMENTS

The photoresist composition of the disclosure will be illustrated.

In the specification, the term “(meth)acrylic monomer” means a monomerhaving a structure of “CH₂═CH—CO—” or “CH₂═C(CH₃)—CO—”, as well as“(meth)acrylate” and “(meth)acrylic acid” mean “an acrylate ormethacrylate” and “an acrylic acid or methacrylic acid,” respectively.Herein, chain structure groups include those having a linear structureand those having a branched structure.

The indefinite articles “a” and “an” are taken as the same meaning as“one or more”.

The term “solid components” means components other than solvents in aresist composition.

The photoresist composition of the disclosure contains

a resin (A1) which has an acid-labile group;

a resin (A2) which has a structural unit represented by formula (I); and

an acid generator.

Herein, the resin (A1) is defined as a resin which has no structuralunit represented by formula (I) but an acid-labile group. The resinwhich has both an acid-labile group and a structural unit represented byformula (I) is defined as “resin (A2)”.

The resin (A1) usually has a structural unit having an acid-labile groupwhich structural unit is sometimes referred to as “structural unit(a1)”. The resin (A1) may further have a structural unit having noacid-labile group.

The structural unit (a1) is derived from a monomer having an acid-labilegroup which is sometimes referred to as “monomer (a1)”.

Herein, the “acid-labile group” means a functional group having aleaving group which is removed therefrom by contacting with an acid togive a hydrophilic group such as a hydroxy group or carboxy group.

Specific examples of the acid-labile group include a group representedby the formula (1):

wherein R^(a1), R^(a2) and R^(a3) each independently represent a C1-C8alkyl group, a C3-C20 alicyclic hydrocarbon group or a combination ofthem, or R^(a1) and R^(a2) may be bonded each other to form a C3-C20divalent alicyclic hydrocarbon group together with the carbon atombonded to both of them, “na” represents an integer of 0 or 1, and *represents a binding site,and a group represented by the formula (2):

wherein R^(a1′) and R^(a2′) each independently represent a hydrogen atomor a C1-C12 hydrocarbon group, and R^(a3′) represents a C1-C20hydrocarbon group, or R^(a3′) is bonded to R^(a1′) or R^(a2′) to form aC2-C20 divalent heterocyclic group with a carbon atom and X bondedthereto, a methylene group in the divalent heterocyclic group may bereplaced by —O— or —S—, X represents an oxygen atom or a sulfur group,and * represents a binding position.

Specific examples of the C1-C8 alkyl group include a methyl group, anethyl group, a propyl group, an isopropyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group and an octyl group.

The alicyclic hydrocarbon group may be monocyclic or polycyclic.Examples of the alicyclic hydrocarbon group include a monocyclicalicyclic hydrocarbon group such as a C3-C20 cycloalkyl group (e.g. acyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group and a cyclooctyl group)and a polycyclic alicyclic hydrocarbon group such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group, a methylnorbornyl group,and the followings.

The alicyclic hydrocarbon group preferably has C3-C16 carbon atoms.

The combination of alkyl group and alicyclic hydrocarbon group includesa methylcyclohexyl group, a dimethylcyclohexyl group and amethylnorbornyl group.

When R^(a1) and R^(a2) of formula (1) are bonded each other to form aC2-C20 divalent hydrocarbon group, examples of the moiety represented by—C(R^(a1))(R^(a2))(R^(a3)) include the following groups and the ringpreferably has 3 to 12 carbon atoms:

wherein R^(a3) is as defined above and * represents a binding site to—O— of formula (1).

Preferred are 1,1′-dialkylalkoxylcarbonyl group, i.e., the grouprepresented by the formula (1) wherein R^(a1), R^(a2) and R^(a3) eachindependently represent a C1-C8 alkyl group, preferably a tert-butylgroup;

2-alkyladaman-2-tyloxycarbonyl group, i.e., the group represented by theformula (1) wherein R^(a1) and R^(a2) are bonded each other to form anadamantyl group and R^(a3) is a C1-C8 alkyl group; and

a 1-(1-adaman-1-tyl)-1-alkylalkoxycarbonyl group, i.e., the grouprepresented by the formula (1) wherein R^(a1) and R^(a2) are C1-C8 alkylgroups and R^(a3) is an adamantyl group.

As to formula (2), examples of the hydrocarbon group include an alkylgroup, an alicyclic hydrocarbon group and an aromatic hydrocarbon group.

Examples of the alkyl group and the alicyclic hydrocarbon group includethe same as described above. Examples of the aromatic hydrocarbon groupinclude an aryl group such as a phenyl group, a naphthyl group, ananthryl group, a p-methylphenyl group, a p-tert-butylphenyl group, ap-adamantylphenyl group, a tolyl group, a xylyl group, a cumyl group, amesityl group, a biphenyl group, a phenanthryl group, a2,6-diethylphenyl group and a 2-methyl-6-ethylphenyl group.

Examples of the divalent heterocyclic group formed by bonding withR^(a2′) or R^(a3′) with a carbon atom and X bonded thereto include thefollowing groups.

In each formula, R^(a1′) and X are as defined above.

It is preferred that at least one of R^(a1′) and R^(a2′) is a hydrogenatom.

Examples of the group represented by formula (2) include the following.

The monomer from which the structural unit (a1) is derived is preferablya compound having an acid-labile group and a carbon-carbon double bond,and is more preferably a (meth)acrylate compound having an acid-labilegroup.

Such (meth)acrylate compound preferably has a C5-C20 alicyclichydrocarbon group. When the photoresist composition has a resin whichhas a structural unit with a bulky structure such as a saturatedalicyclic hydrocarbon group, the photoresist composition can provide aphotoresist pattern with excellent resolution.

The total content of the structural unit (a1) is usually 10 to 95% bymole, preferably 10 to 90% by mole, more preferably 20 to 85% by molebased on all the structural units of the resin (A1).

Specific examples of the structural unit derived from the (meth)acrylatecompound having a group of formula (1) include those represented by theformula (a1-0):

wherein L^(a01) each independently represents an oxygen atom or*—O—(CH₂)_(k01)—CO—O— in which * represents a binding site to —CO—, andk01 represents an integer of 1 to 7;

R^(a01) each independently represent a hydrogen atom or a methyl group;R^(a02), R^(a03) and R^(a04) each independently represent a C1-C8 alkylgroup, a C3-C18 alicyclic hydrocarbon group, or a combination of them.Specific examples of the structural unit derived from the (meth)acrylatecompound having an acid-labile group include those represented by theformulae (a1-1) and (a1-2):

wherein L^(a1) and L^(a2) each independently represents an oxygen atomor *—O—(CH₂)_(k1)—CO—O— in which * represents a binding site to —CO—,and k1 represents an integer of 1 to 7;R^(a4) and R^(a5) each independently represent a hydrogen atom or amethyl group;R^(a6) and R^(a7) each independently represent a C1-C8 alkyl group, aC3-C18 alicyclic hydrocarbon group, or a combination of them;“m1” represents an integer of 0 to 14; “n1” represents an integer of 0to 10; and “n1′” represents 0 to 3.The structural units represented by the formulae (a1-0), (a1-1) and(a1-2) are sometimes referred to as “structural unit (a1-0)”,“structural unit (a1-1)” and “structural unit (a1-2)”, respectively.L^(a01) is preferably an oxygen atom or *—O—(CH₂)_(f01)—CO—O— in which *represents a binding site to —CO—, and “f01” represents an integer of 1to 4, and is more preferably an oxygen atom.“f01” represents preferably an integer of 1 to 4, more preferably 1.Examples of the alkyl group, the alicyclic hydrocarbon group and thecombination of them, represented by R^(a02), R^(a03) and R^(a04),include those same as examples of the alkyl group represented by R^(a1),R^(a2) and R^(a3).The alkyl group represented by R^(a02), R^(a03) or R^(a04) is preferablya C1-C6 alkyl group.The alicyclic hydrocarbon group represented by R^(a02), R^(a03) orR^(a04) has preferably 12 or less, and more preferably 6 or less ofcarbon atoms.The combination of the alkyl group and the alicyclic hydrocarbon, as agroup represented by R^(a02), R^(a03) or R^(a04), has preferably 18 orless of carbon atoms. Examples of the combination include amethylcyclohexyl group, dimethylcyclohexyl group, a methylnorbornylgroup, a methyladamantyl group, a (cyclohexyl)methyl group, a methylcyclohexylmethyl group, an adamantylmethyl group, and a norbornylmethylgroup.R^(a02) and R^(a03) are each preferably a C1-C6 alkyl group, morepreferably a methyl group or an ethyl group.R^(a04) is preferably a C1-C6 alkyl group or a C5-C12 alicyclichydrocarbon group, more preferably a methyl group, an ethyl group, acyclohexyl group or an adamantyl group.L^(a1) and L^(a2) are preferably an oxygen atom or *—O—(CH₂)_(f1)—CO—O—in which * represents a binding site to —CO—, and “f1” represents aninteger of 1 to 4, and is more preferably an oxygen atom.

“f1” represents preferably an integer of 1 to 4, more preferably aninteger of 1.

R^(a4) and R^(a5) are each preferably a methyl group.Examples of the alkyl group, the alicyclic hydrocarbon group and thecombination of them, represented by R^(a6) and R^(a7), include thosesame as examples for R^(a1), R^(a2) and R^(a3).The alkyl group represented by R^(a6) or R^(a7) is preferably a C1-C6alkyl group.The alicyclic hydrocarbon group represented by R^(a6) or R^(a7) haspreferably 8 or less, more preferably 6 or less of carbon atoms.“m1” is preferably an integer of 0 to 3, and more preferably 0 or 1.“n1” is preferably an integer of 0 to 3, and more preferably 0 or 1.“n1′” is preferably 0 or 1.The structural unit (a1-0) is preferably one represented by any one ofthe following formulae, and more preferably one represented by any oneof formulae (a1-0-1) to (a1-0-10).

Other examples of the structural unit (a1-0) include those representedby the above-mentioned formulae in which a methyl group bonded to itsmain chain has been replaced by a hydrogen atom.Examples of the monomer from which the structural unit (a1-1) is derivedinclude those as recited in JP2010-204646A1. Among them, preferred arethose represented by of formulae (a1-1-1) to (a1-1-8), and morepreferred are those represented by of formulae (a1-1-1) to (a1-1-4).

Examples of the monomer from which the structural unit (a1-2) is derivedinclude 1-ethyl-cyclopentan-1-yl(meth)acrylate,1-ethyl-cyclohexan-1-yl(meth)acrylate, 1-ethyl-cyclohept-1-yl(meth)acrylate, 1-methyl-cyclopent-1-yl(meth)acrylate,1-methyl-cyclohex-1-yl(meth)acrylate,1-isopropyl-cyclopent-1-yl(meth)acrylate, and1-isopropyl-cyclohex-1-yl(meth)acrylate.As the monomer from which the structural unit (a1-2) is derived,preferred are those represented by formulae (a1-2-1) to (a1-2-12), morepreferred are those represented by formulae (a1-2-3), (a1-2-4), (a1-2-9)and (a1-2-10), more preferred are those represented by formulae (a1-2-3)and (a1-2-9).

When the resin (A1) has at least one structural unit represented byformulae (a1-0), (a1-1) and (a1-2), the content of the structural unitin the resin is usually 10 to 95% by mole, preferably 15 to 90% by mole,and more preferably 20 to 85% by mole based on all the structural unitsof the resin (A1).Examples of the structural unit (a1) having the group represented byformula (1) include a structural unit presented by formula (a1-3).

The structural unit represented by formula (a1-3) is sometimes referredto as “structural unit (a1-3)”. The monomer from which the structuralunit (a1-3) is derived is sometimes referred to as “monomer (a1-3)”.

In the formula, R^(a9) represents a carboxy group, a cyano group, a—COOR^(a13), a hydrogen atom or a C₁ to C₃ aliphatic hydrocarbon groupthat may have a hydroxy group,

R^(a13) represents a C₁ to C₈ aliphatic hydrocarbon group, a C₃ to C₂₀alicyclic hydrocarbon group or a group formed by combining thereof, ahydrogen atom contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by a hydroxy group, amethylene group contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by an oxygen atom or acarbonyl group, and

R^(a10), R^(a11) and R^(a12) each independently represent a C₁ to C₈alkyl group, a C₃ to C₂₀ alicyclic hydrocarbon group or a group formedby combining thereof, or R^(a10) and R^(a11) may be bonded together witha carbon atom bonded thereto to form a C₂ to C₂₀ divalent hydrocarbongroup.

Here, examples of —COOR^(a13) group include a group in which a carbonylgroup is bonded to the alkoxy group, such as methoxycarbonyl andethoxycarbonyl groups.

Examples of the aliphatic hydrocarbon group that may have a hydroxygroup for R^(a9) include methyl, ethyl, propyl, hydroxymethyl and2-hydroxyethyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group for R^(a13) includemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the C₃ to C₂₀ alicyclic hydrocarbon group for R^(a13)include cyclopentyl, cyclopropyl, adamantyl, adamantylmetyl,1-(adamantyl-1-yl)-methylethyl, 2-oxo-oxolane-3-yl and2-oxo-oxolane-4-yl groups.

Examples of the alkyl group for R^(a10) to R^(a12) include methyl,ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group for R^(a10) and R^(a12)include monocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl groups; andpolycyclic groups such as decahydronaphtyl, adamantyl,2-alkyl-2-adamantyl, 1-(adamantane-1-yl)alkane-1-yl, norbornyl,methylnorbornyl and isobornyl groups.

When R^(a10) and R^(a11) are bonded together with a carbon atom bondedthereto to form a divalent hydrocarbon group, examples of thegroup-C(R^(a10))(R^(a11))(R^(a12)) include the following groups.

In each formula, R^(a12) is as defined above.

Examples of the monomer (a1-3) include tert-butyl5-norbornene-2-carboxylate, 1-cyclohexyl-1-methylethyl5-norbornene-2-carboxylate, 1-methylcyclohexyl5-norbornene-2-carboxylate, 2-methy-2-adamantane-2-yl5-norbornene-2-carboxylate, 2-ethyl-2-adamantane-2-yl5-norbornene-2-carboxylate, 1-(4-methycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-(4-hydroxycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-methyl-(4-oxocyclohexyl)-1-ethyl5-norbornene-2-carboxylate, and 1-(1-adamantane-1-yl)-1-methylethyl5-norbornene-2-carboxylate.

The resin (A1) which has the structural unit (a1-3) can improve theresolution of the obtained resist composition because it has a bulkystructure, and also can improve a dry-etching tolerance of the obtainedphotoresist composition because of incorporated a rigid norbornene ringinto a main chain of the resin (A1).

When the resin (A1) has the structural unit (a1-3), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, based on the all the structural units of the resin (A1) (100% bymole).

Examples of a structural unit (a1) having the group represented byformula (2) include a structural unit represented by formula (a1-4). Thestructural unit is sometimes referred to as “structural unit (a1-4)”.

In the formula, R^(a32) represents a hydrogen atom, a halogen atom or aC₁ to C₆ alkyl group that may have a halogen atom,

R^(a33) in each occurrence independently represent a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group,

“1a” represents an integer 0 to 4,

R^(a34) and R^(a35) each independently represent a hydrogen atom or a C₁to C₁₂ hydrocarbon group; and

R^(a36) represents a C₁ to C₂₀ hydrocarbon group, or R^(a35) and R^(a36)may be bonded together with a C—O bonded thereto to form a divalent C₃to C₂₀ heterocyclic group, and a methylene group contained in thehydrocarbon group or the divalent heterocyclic group may be replaced byan oxygen atom or a sulfur atom.

Examples of the alkyl group of R^(a32) and R^(a33) include methyl,ethyl, propyl, isopropyl, butyl, pentyl and hexyl groups. The alkylgroup is preferably a C₁ to C₄ alkyl group, and more preferably a methylgroup or an ethyl group, and still more preferably a methyl group.

Examples of the halogen atom of R^(a32) and R^(a33) include a fluorine,chlorine, bromine and iodine atoms.

Examples of the alkyl group that may have a halogen atom includetrifluoromethyl, difluoromethyl, methyl, perfluoroethyl,1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl,1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

Examples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy and hexyloxy groups. The alkoxy group is preferably a C₁ to C₄alkoxy group, more preferably a methoxy group or an ethoxy group, andstill more preferably a methoxy group.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the acyloxy group include acetyloxy, propionyloxy andbutyryloxy groups.

Examples of the hydrocarbon group for R^(a34) and R^(a35) are the sameexamples as described in R^(a1′) to R^(a2′) in the formula (2).

Examples of hydrocarbon group for R^(a36) include a C₁ to C₁₈ alkylgroup, a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a group formed by combining thereof.

In the formula (a1-4), R^(a32) is preferably a hydrogen atom.

R^(a33) is preferably a C₁ to C₄ alkoxy group, more preferably a methoxygroup or an ethoxy group, and still more preferably a methoxy group.

“1a” is preferably 0 or 1, and more preferably 0.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a C₁ to C₁₂ hydrocarbon group, and more preferablya methyl group or an ethyl group.

The hydrocarbon group for R^(a36) is preferably a C₁ to C₁₈ alkyl group,a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a combination thereof, and more preferably a C₁ toC₁₈ alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a C₇ to C₁₈aralkyl group. The alkyl group and the alicyclic hydrocarbon group forR^(a36) are preferably unsubstituted. When the aromatic hydrocarbongroup of R^(a36) has a substituent, the substituent is preferably a C₆to C₁₀ aryloxy group.

Examples of the monomer from which the structural unit (a1-4) is derivedinclude monomers described in JP2010-204646A1. Among these, the monomersare preferably the following monomers represented by formula (a1-4-1) toformula (a1-4-8), and more preferably monomers represented by formula(a1-4-1) to formula (a1-4-5), and formula (a1-4-8).

When the resin (A1) has the structural unit (a1-4), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, based on the all the structural units of the resin (A1) (100% bymole).

Another example of the structural unit (a1) includes a structural unitrepresented by the formula (a-5).

In the formula (a1-5), R^(a8) represents a hydrogen atom, a halogen atomor a C₁ to C₆ alkyl group that may have a halogen atom,

Z^(a1) represent a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-, where h3represents an integer of 1 to 4, * represents a binding site to

L⁵¹, and L⁵⁴ represents —O— or —S—

L⁵¹, L⁵² and L⁵³ each independently represent —O— or —S—,

“s1” represents an integer of 1 to 3, and

“s1′” represents an integer of 0 to 3.

The structural unit represented by the formula (a1-5) is sometimesreferred to as “structural unit (a1-5)”.R^(a8) is preferably a hydrogen atom, a methyl group or atrifluoromethyl group.L⁵¹ is preferably —O—.L⁵² and L⁵³ are independently preferably —O— or —S—, and more preferablyone is —O— and another is —S—.“s1” is preferably 1.“s1′” is preferably an integer of 0 to 2.Z^(a1) is preferably a single bond or *—CH₂—CO—O— where * represents abinding site to L⁵¹.Examples of the monomer from which the structural unit (a-5) is derivedinclude the monomers described in JP2010-61117A1. Among these, themonomers are preferably the following monomers represented by formula(a1-5-1) to formula (a1-5-4), and more preferably monomers representedby formula (a1-5-1) and formula (a1-5-2).

When the resin (A1) has a structural unit (a1-5), the content of thestructural unit is usually 1 to 50% by mole, preferably 3 to 45% by moleand more preferably 5 to 40% by mole based on all the structural unitsof the resin.

The resin (A1) has, as the structural unit (a1), preferably at leastone, more preferably two or more structural units selected from thestructural unit (a1-0), the structural unit (a1-1), the structural unit(a1-2) and the structural unit (a1-5), still more preferably acombination of the structural unit (a1-1) and the structural unit(a1-2), a combination of the structural unit (a1-1) and the structuralunit (a1-5), a combination of the structural unit (a1-1) and thestructural unit (a1-0), a combination of the structural unit (a1-2) andthe structural unit (a1-0), a combination of the structural unit (a1-5)and the structural unit (a1-0), a combination of the structural unit(a1-0), the structural unit (a1-1) and the structural unit (a1-2), acombination of the structural unit (a1-0), the structural unit (a1-1)and the structural unit (a1-5), and further still preferably acombination of the structural unit (a1-1) and the structural unit(a1-2), a combination of the structural unit (a1-1) and the structuralunit (a1-5).

The resin (A1) may further have a structural unit having no acid-labilegroup.

The structural unit having no acid-labile group preferably has a hydroxygroup or a lactone ring. The structural unit having no acid-labile groupis sometimes referred to as “structural unit (s)”.

The structural unit having no acid-labile group but having a hydroxygroup is sometimes referred to as “structural unit (a2)”, and thestructural unit having no acid-labile group but having a lactone ring issometimes referred to as “structural unit (a3)”.When the photoresist composition has the structural unit (s), itsresolution of photoresist pattern and its adhesiveness with a substratecan be improved. These structural units can be suitably selecteddepending on exposure source for producing photoresist pattern from thephotoresist composition.

When KrF excimer laser (wavelength: 248 nm) lithography system, or ahigh energy laser such as electron beam and extreme ultraviolet is usedas an exposure system, preferred is a resin which has the structuralunit having no acid-labile group but having a phenolic-hydroxy group.

When ArF excimer laser (wavelength: 193 nm) is used as an exposuresystem, preferred is a resin which has the structural unit having noacid-labile group but having an alcoholic hydroxy group, and morepreferred is a resin which has the structural unit represented by thefollowing formula (a2-1).

Preferred examples of the structural unit (a2) include a structural unitrepresented by the formula (a2-0), which is sometimes referred to as“structural unit (a2-0)”:

wherein R^(a30) represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom,R^(a31) in each occurrence independently represents a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group, and“ma” represents an integer 0 to 4.

Examples of the alkyl group include methyl, ethyl, propyl, butyl,n-pentyl and n-hexyl groups.

Examples of the halogen atom include a chlorine atom, a fluorine atomand bromine atom.

Examples of the C₁ to C₆ alkyl group that may have a halogen atom forR^(a30) include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

R^(a30) is preferably a hydrogen atom or a C₁ to C₄ alkyl group, andmore preferably a hydrogen atom, a methyl group or an ethyl group, andstill more preferably a hydrogen atom or a methyl group.

Examples of the alkoxy group for R^(a31) include methoxy, ethoxy,propoxy, butoxy, pentyloxy, and hexyloxy groups. R^(a31) is preferably aC₁ to C₄ alkoxy group, more preferably a methoxy group or an ethoxygroup, and still more preferably a methoxy group.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the acyloxy group include acetyloxy, propionyloxy andbutyryloxy groups.

“ma” is preferably 0, 1 or 2, more preferably 0 or 1, still morepreferably 0.

Examples of a monomer from which the structural unit (a2-0) is derivedinclude monomers described in JP2010-204634A1.

The structural unit (a2-0) is preferably a structural unit representedbelow.

Among these, a structural unit represented by formula (a2-0-1) andformula (a2-0-2) are preferred.

The resin (A1) which further has the structural units (a2-0) can beproduced, for example, by polymerizing a monomer where its phenolichydroxy group has been protected with a suitable protecting group,followed by deprotection. The deprotection is carried in such a mannerthat an acid-labile group in the structural unit (a1) is significantlyimpaired. Examples of the protecting group for a phenolic hydroxy groupinclude an acetyl group.

When the resin (A1) further has the structural unit (a2-0), theproportion thereof is preferably 5% by mole to 95% by mole, morepreferably 10% by mole to 80% by mole, and still more preferably 15% bymole to 80% by mole, with respect to the total structural units (100% bymole) constituting the resin (A1).

Preferred examples of the structural unit (a2) include a structural unitrepresented by the formula (a2-1):

wherein R^(a14) represents a hydrogen atom or a methyl group, R^(a15)and R^(a16) each independently represent a hydrogen atom, a methyl groupor a hydroxy group, L^(a3) represents an oxygen atom or*—O—(CH₂)_(k2)—CO—O— in which * represents a binding site to —CO—, andk2 represents an integer of 1 to 7, and o1 represents an integer of 0 to10. In the formula (a2-1), L^(a3) is preferably an oxygen atom or*—O—(CH₂)_(f2)—CO—O— in which * represents a binding site to —CO—, andf2 represents an integer of 1 to 4, is more preferably an oxygen atomand *—O—CH₂—CO—O—, and is still more preferably an oxygen atom.R^(a14) is preferably a methyl group.R^(a15) is preferably a hydrogen atom.R^(a16) is preferably a hydrogen atom or a hydroxy group.o1 is preferably 0, 1, 2 or 3 and is more preferably 0 or 1.

Examples of the monomer from which the structural unit represented bythe formula (a2-1) is derived include those mentioned inJP2010-204646A1, preferably those represented by formulae (a2-1-1),(a2-1-2), (a2-1-3), (a2-1-4), (a2-1-5) and (a2-1-6), and more preferablythose represented by formulae (a2-1-1), (a2-1-2), (a2-1-3) and (a2-1-4),still more preferably those represented by formulae (a2-1-1) and(a2-1-3).

When the resin (A1) further has the structural unit represented by theformula (a2-1), the content of the structural unit represented by theformula (a2-1) is usually 1 to 45% by mole and preferably 1 to 40% bymole, more preferably 1 to 35% by mole, still more preferably 2 to 20%by mole, based on all the structural units of the resin (A1).

In the structural unit (a3), examples of the lactone ring include amonocyclic lactone ring such as β-propiolactone ring, γ-butyrolactonering and δ-valerolactone ring, and a condensed ring formed from amonocyclic lactone ring and the other ring. Among them, preferred areγ-butyrolactone ring and a condensed lactone ring formed fromγ-butyrolactone ring and another ring.

Preferable examples of the structural unit (a3) include thoserepresented by the formulae (a3-1), (a3-2), (a3-3) and (a3-4):

wherein L^(a4), L^(a5) and L^(a6) each independently represent *—O— or*—O—(CH₂)_(k3)—CO—O— in which * represents a binding site to —CO— and k3represents an integer of 1 to 7,L^(a7) represents a single bond, *-L^(a8)-O—, *-L^(a8)-CO—O—,*-L^(a8)-CO—O-L^(a9)-CO—O—, or *-L^(a8)-O—CO-L^(a9)-O—; * represents abinding site to a carbonyl group, L^(a8) and L^(a9) each represent aC1-C6 alkanediyl group,R^(a18), R^(a19) and R^(a20) each independently represent a hydrogenatom or a methyl group,R^(a21) represents a C1-C4 aliphatic hydrocarbon group, R^(a22) andR^(a23) are independently in each occurrence a carboxyl group, a cyanogroup or a C1-C4 aliphatic hydrocarbon group, R^(a24) represents ahydrogen atom, a halogen atom or a C1-C6 alkyl group optionally having ahalogen atom, and p1 represents an integer of 0 to 5, q1 and r1independently each independently represent an integer of 0 to 3.Examples of the aliphatic hydrocarbon group for R^(a21), R^(a22) andR^(a23) include an alkyl group such as methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl and tert-butyl groups.

Examples of the halogen atom for R^(a24) include fluorine, chlorine,bromine and iodine atoms.

Examples of the alkyl group for R^(a24) include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups.The alkyl group is preferably a C₁ to C₄ alkyl group, more preferably amethyl group or an ethyl group.

Examples of the alkyl group having a halogen atom for R^(a24) includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl andtriiodomethyl groups.

R^(a24) is preferably a hydrogen atom or a C₁ to C₄ alkyl group, morepreferably a hydrogen atom, a methyl group or an ethyl group, and stillmore preferably a hydrogen atom or a methyl group.

Examples of the alkanediyl group of L^(a8) and L^(a9) include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl, pentane-1,4-diyl and2-methylbutane-1,4-diyl groups.

L^(a4), L^(a5) and L^(a6) each independently represent preferably —O— or*—O—(CH₂)_(d1)—CO—O— in which * represents a binding site to —CO— and d1represents an integer of 1 to 4, and more preferably —O— and*—O—CH₂—CO—O—, and still more preferably —O—.

L^(a7) represents preferably a single bond or *-L^(a8)-CO—O—, and morepreferably a single bond, *—CH₂—CO—O— or *—C₂H₄—CO—O—.

Preferably, R^(a18), R^(a19) and R^(a20) are independently in eachoccurrence a methyl group.

Preferably, R^(a22) and R^(a23) are independently in each occurrence acarboxyl group, a cyano group or a methyl group.

p1, q1 and r1 are independently in each occurrence preferably an integerof 0 to 2, and more preferably 0 or 1.

Examples of the monomers from which the structural unit (a3) is derivedinclude those mentioned in JP2010-204646A1. Examples of monomers fromwhich the structural unit (a3) is derived include preferably thoserepresented by the formulae (a3-1-1), (a3-1-2), (a3-1-3) and (a3-1-4),the formulae (a3-2-1), (a3-2-2), (a3-2-3) and (a3-2-4), the formulae(a3-3-1), (a3-3-2), (a3-3-3) and (a3-3-4), and the formulae (a3-4-1) to(a3-4-12), more preferably those represented by the formulae (a3-1-1),(a3-1-2), (a3-2-3), (a3-2-4), (a3-4-1) to (a3-4-12), still morepreferably those represented by the formulae (a3-4-1) to (a3-4-12), andfurther more preferably those represented by the formulae (a3-4-1) to(a3-4-6).

Examples of the structural unit (a3) further include those representedby formulae (a3-4-1) to (a3-4-12) in which a methyl group has beenreplaced by a hydrogen atom.

The content of the structural unit (a3) is usually 5 to 70% by mole andpreferably 10 to 65% by mole, more preferably 10 to 60% by mole, basedon all the structural units of the resin (A1).

The resin (A1) may further have a structural unit other than thestructural units (a1), (a2) and (a3). The structural unit other than thestructural units (a1), (a2) and (a3) is sometimes referred to as the“structural unit (t)”.

Examples of the structural unit (t) include a structural unit having ahalogen atom and a structural unit which has a hydrocarbon group havingno acid-labile group.

Examples of the structural unit having a halogen atom, which structuralunit is sometimes referred to as “structural unit (a4)”, include astructural unit represented by formula (a4-0).

In the formula (a4-0), R⁵ represents a hydrogen atom or a methyl group,

L⁵ represents a single bond or a C₁ to C₄ saturated aliphatichydrocarbon group,

L³ represents a C₁ to C₈ perfluoroalkanediyl group, or a C₃ to C₁₂perfluorocycloalkanediyl group, and

R⁶ represents a hydrogen atom or a fluorine atom.

Examples of the saturated aliphatic hydrocarbon group for L⁵ include C₁to C₄ alkanediyl group, i.e., a linear alkanediyl group such asmethylene, ethylene, propane-1,3-diyl, and butane-1,4-diyl groups; and abranched alkanediyl group ethane-1,1-diyl, propane-1,2-diyl,butane-1,3-diyl, 2-methylpropane-1,3-diyl and 2-methylpropane-1,2-diylgroups.

L⁵ is preferably a single bond, methylene or ethylene group, and morepreferably a single bond or methylene group.

Examples of the perfluoroalkanediyl group for L³ includedifluoromethylene, perfluoroethylene, perfluoroethyl fluoromethylene,perfluoropropane-1,3-diyl, perfluoropropane-1,2-diyl,perfluoropropane-2,2-diyl, perfluorobutane-1,4-diyl,perfluorobutane-2,2-diyl, perfluorobutane-1,2-diyl,perfluoropentane-1,5-diyl, perfluoropentane-2,2-diyl,perfluoropentane-3,3-diyl, perfluorohexane-1,6-diyl,perfluorohexane-2,2-diyl, perfluorohexane-3,3-diyl,perfluoroheptane-1,7-diyl, perfluoroheptane-2,2-diyl,perfluoroheptane-3,4-diyl, perfluoroheptane-4,4-diyl,perfluorooctan-1,8-diyl, perfluorooctan-2,2-diyl,perfluorooctan-3,3-diyl and perfluorooctan-4,4-diyl groups.

Examples of the perfluoro cycloalkanediyl group for L³ includeperfluorocyclohexanediyl, perfluorocyclopentanediyl,perfluorocycloheptanediyl and perfluoroadamantanediyl groups.

L³ is preferably a C₁ to C₆ perfluoroalkanediyl group, more preferably aC₁ to C₃ perfluoroalkanediyl group.

Examples of the structural unit represented by formula (a4-0) includethose as follow.

Examples of the structural unit represented by formula (a4-0) includethe structural units represented by the above formulae in which a methylgroup corresponding to R⁵ has been replaced by a hydrogen atom.

Examples of the structural unit (a4) include those represented byformula (a4-1):

wherein R^(a41) represents a hydrogen atom or a methyl group,

R^(a42) represents an optionally substituted C₁ to C₂₀ hydrocarbon groupwhere a methylene group may be replaced by an oxygen atom or a carbonylgroup, and

A^(a41) represents an optionally substituted C₁ to C₆ alkanediyl groupor a group represented by formula (a-g1):

wherein s represents 0 or 1,

A^(a42) and A^(a44) each independently represent an optionallysubstituted C₁ to C₅ aliphatic hydrocarbon group,

A^(a43) represents a single bond or an optionally substituted C₁ to C₅aliphatic hydrocarbon group, and

X^(a41) and X^(a42) each independently represent —O—, —CO—, —CO—O— or—O—CO—,

provided that the total number of the carbon atoms contained in thegroup of A^(a42), A^(a43), A^(a44), X^(a41) and X^(a42) is 7 or less, atleast one of A^(a41) and R^(a42) has a halogen atom as a substituent,and

* and ** represent a binding site, and * represents a binding site to—O—CO—R^(a42).

The hydrocarbon group for R^(a42) may be a chain aliphatic hydrocarbongroup, a cyclic aliphatic hydrocarbon group, an aromatic hydrocarbongroup, or a combination thereof.

The chain aliphatic hydrocarbon group and the cyclic aliphatichydrocarbon group may have a carbon-carbon unsaturated bond, and ispreferably a chain and a cyclic saturated aliphatic hydrocarbon group.Examples of the saturated aliphatic hydrocarbon group include a linearor branched alkyl group, a monocyclic or polycyclic alicyclichydrocarbon group, and an aliphatic hydrocarbon group formed bycombining the alkyl group and the alicyclic hydrocarbon group.

Examples of the chain aliphatic hydrocarbon group include an alkyl groupsuch as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl and hexadecyl groups.

Examples of the alicyclic hydrocarbon group include a cycloalkyl groupsuch as cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups; andpolycyclic hydrocarbon groups such as decahydronaphtyl, adamantyl andnorbornyl groups as well as groups below. * represents a binding site.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, biphenyl, phenanthryl and fluorenyl groups.

The hydrocarbon group for R^(a42) is preferably a chain aliphatichydrocarbon group, a cyclic aliphatic hydrocarbon group, and acombination thereof. The hydrocarbon group may have a carbon-carbonunsaturated bond, is preferably a chain saturated aliphatic hydrocarbongroup, a cyclic saturated aliphatic hydrocarbon group, and a combinationthereof.

Examples of the substituent for R^(a42) include a halogen atom and agroup represented by formula (a-g3):

*—X^(a43)-A^(a45)  (a-g3)

wherein X^(a43) represent an oxygen atom, a carbonyl group, acarbonyloxy group or an oxycarbonyl group,

A^(a45) represents a C₁ to C₁₇ aliphatic hydrocarbon group that has ahalogen atom, and

* represents a binding site.

Examples of the halogen atom include fluorine, chlorine, bromine oriodine atom, and preferably a fluorine atom.

Examples of the aliphatic hydrocarbon group for A^(a45) include the sameones as those for R^(a42).

R^(a42) is preferably an aliphatic hydrocarbon group that may have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or an aliphatic hydrocarbon group having the group represented bythe formula (a-g3).

When R^(a42) is an aliphatic hydrocarbon group having a halogen atom, analiphatic hydrocarbon group having a fluorine atom is preferred, aperfluoroalkyl group or a perfulorocycloalkyl group are more preferred,a C₁ to C₆ perfluoroalkyl group is still more preferred, a C₁ to C₃perfluoroalkyl group is particularly preferred.

Examples of the perfluoroalkyl group include perfluoromethyl,perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl,perfluorohexyl, perfluoroheptyl and perfluorooctyl groups. Examples ofthe perfluorocycloalkyl group include perfluorocyclohexyl group.

The aliphatic hydrocarbon group having the group represented by theformula (a-g3) is more preferably a group represented by formula (a-g2):

*-A^(a46)-X^(a44)-A^(a47)  (a-g2)

wherein A^(a46) represents a C₁ to C₁₇ aliphatic hydrocarbon group thatmay have a halogen atom,

X^(a44) represent a carbonyloxy group or an oxycarbonyl group,

A^(a47) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may havea halogen atom,

provided that the total number of the carbon atoms contained in thegroup of A^(a46), X^(a44) and A^(a47) is 18 or less,

at least one of A^(a46) and A^(a47) has a halogen atom, and

* represents a binding site to a carbonyl group.

The aliphatic hydrocarbon group for A^(a46) has preferably 1 to 6 carbonatoms, more preferably 1 to 3, carbon atoms.

The aliphatic hydrocarbon group for A^(a47) has preferably 4 to 15carbon atoms, more preferably 5 to 12 carbon atoms. A^(a47) is morepreferably a cyclohexyl group or an adamantyl group.

Preferred examples of *-A^(a46)-X^(a44)-A^(a47) include the followingones.

Examples of the alkanediyl group for A^(a41) include a linear alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups; a branched alkanediyl groupsuch as propane-1,2-diyl, butan-1,3-diyl, 2-methylpropane-1,2-diyl,1-methylbutane-1,4-diyl, 2-methylbutane-1,4-diyl groups.

Examples of the substituent on the alkanediyl group for A^(a41) includea hydroxy group and a C₁ to C₆ alkoxy group.

A^(a41) is preferably a C₁ to C₄ alkanediyl group, more preferably a C₂to C₄ alkanediyl group, and still more preferably ethylene group.

In the group represented by the formula (a-g1) (which is sometimesreferred to as “group (a-g1)”), examples of the aliphatic hydrocarbongroup for A^(a42), A^(a43) and A^(a44) include methylene, ethylene,propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,1-methylpropane-1,3-diyl, 2-methylpropane-1,3-diyl and2-methylpropane-1,2-diyl groups.

Examples of the substituent on the aliphatic hydrocarbon group forA^(a42), A^(a43) and A^(a44) include a hydroxy group and a C₁ to C₆alkoxy group.

s is preferably 0.

Examples of the group (a-g1) in which X^(a42) represents an oxygen atom,a carbonyl group, a carbonyloxy group, or an oxycarbonyl group includethe following ones. In the formula, * and ** each represent a bindingsite, and ** represents a binding site to —O—CO—R^(a42).

The structural unit represented by the formula (a4-1) is preferablystructural units represented by formula (a4-2) and formula (a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group,

A^(f1) represent a C₁ to C₆ alkanediyl group, and

R^(f2) represents a C₁ to C₁₀ hydrocarbon group that has a fluorineatom;

where R^(f11) represents a hydrogen atom or a methyl group,

A^(f11) represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ aliphatic hydrocarbon group that may havea fluorine atom,

X^(f12) represents an oxycarbonyl group or a carbonyloxy group,

A^(f14) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may havea fluorine atom, and

provided that at least one of A^(f23) and A^(f14) represents analiphatic hydrocarbon group having a fluorine atom.

Examples of the alkanediyl group for A^(f1) include a linear alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl,butane-1,4-diyl, pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as 1-methylpropane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,1-methylbutane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

Examples of the hydrocarbon group for R^(f2) include an aliphatichydrocarbon group and an aromatic hydrocarbon group. The aliphatichydrocarbon group includes chain and cyclic groups, and a combinationthereof. The aliphatic hydrocarbon group is preferably an alkyl groupand a cyclic aliphatic hydrocarbon group.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and2-ethylhexyl groups.

Examples of the cyclic aliphatic hydrocarbon group include any of amonocyclic group and a polycyclic group. Examples of the monocyclicalicyclic hydrocarbon group include a cycloalkyl group such ascyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl groups.Examples of the polycyclic hydrocarbon groups includesdecahydronaphthyl, adamantyl, 2-alkyladamantane-2-yl,1-(adamantane-1-yl) alkane-1-yl, norbornyl, methylnorbornyl andisobornyl groups.

Examples of the hydrocarbon group having a fluorine atom for R^(f2)include an alkyl group having a fluorine atom and an alicyclichydrocarbon group having a fluorine atom.

Specific examples of an alkyl group having a fluorine atom include afluorinated alkyl group such as difluoromethyl, trifluoromethyl,1,1-difluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl,perfluoroethyl, 1,1,2,2-tetrafluoropropyl, 1,1,2,2,3,3-hexafluoropropyl,perfluoroethylmethyl, 1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl,perfluoropropyl, 1-(trifluoromethyl)-2,2,2-trifluoroethyl,perfluoropropyl, 1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, perfluorobutyl,1,1-bis(trifluoro)methyl-2,2,2-trifluoroethyl, 2-(perfluoropropyl)ethyl,1,1,2,2,3,3,4,4-octafluoropentyl, perfluoropentyl,1,1,2,2,3,3,4,4,5,5-decafluoropentyl,1,1-bis(trifluoromethyl)2,2,3,3,3-pentafluoropropyl,2-(perfluorobutyl)ethyl, 1,1,2,2,3,3,4,4,5,5-decafluorohexyl,1,1,2,2,3,3,4,4,5,5,6,6-dodeca fluorohexyl, perfluoropentylmethyl andperfluorohexyl groups.

Examples of the alicyclic hydrocarbon group having a fluorine atominclude a fluorinated cycloalkyl group such as perfluorocyclohexyl andperfluoroadamantyl groups.

In the formula (a4-2), A^(f1) is preferably a C₂ to C₄ alkanediyl group,and more preferably an ethylene group.

R^(f2) is preferably a C₁ to C₆ fluorinated alkyl group.

Examples of the alkanediyl group for A^(f11) include the same ones asthose for A^(f1).

Examples of the aliphatic hydrocarbon group for A^(f13) include any of adivalent chain or cyclic aliphatic hydrocarbon group, or a combinationthereof. The aliphatic hydrocarbon group may have a carbon-carbonunsaturated bond, and is preferably a saturated aliphatic hydrocarbongroup.

The aliphatic hydrocarbon group that may have a fluorine atom forA^(f13) is preferably a saturated aliphatic hydrocarbon group that mayhave a fluorine atom, and more preferably perfuloroalkandiyl group.

Examples of the divalent chain aliphatic hydrocarbon that may have afluorine atom include an alkanediyl group such as methylene, ethylene,propanediyl, butanediyl and pentanediyl groups; a perfluoroalkanediylgroup such as difluoromethylene, perfluoroethylene,perfluoropropanediyl, perfluorobutanediyl and perfluoropentanediylgroups.

The divalent cyclic aliphatic hydrocarbon group that may have a fluorineatom is any of monocyclic hydrocarbon group and polycyclic hydrocarbongroup.

Examples of the monocyclic aliphatic hydrocarbon group includecyclohexanediyl and perfluorocyclohexanediyl groups.

Examples of the polycyclic aliphatic hydrocarbon group includeadamantanediyl, norbornanediyl and perfluoroadamantanediyl groups.

Examples of the aliphatic hydrocarbon group for A^(f14) include any of achain aliphatic hydrocarbon group, a cyclic aliphatic hydrocarbon groupand a combination thereof. The aliphatic hydrocarbon group may have acarbon-carbon unsaturated bond, and is preferably a saturated aliphatichydrocarbon group.

The aliphatic hydrocarbon group that may have a fluorine atom forA^(f14) is preferably the saturated aliphatic hydrocarbon group that mayhave a fluorine atom.

Examples of the chain aliphatic hydrocarbon group that may have ahalogen atom include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, pentyl, hexyl, perfluorohexyl,hepthyl, perfluoroheptyl, octyl and perfluorooctyl groups.

The cyclic aliphatic hydrocarbon group that may have a fluorine atom maybe any of a monocyclic hydrocarbon group and a polycyclic hydrocarbongroup. Examples of the group containing the monocyclic aliphatichydrocarbon group include cyclopropylmethyl, cyclopropyl,cyclobutylmethyl, cyclopentyl, cyclohexyl and perfluorocyclohexylgroups. Examples of the group containing the polycyclic aliphatichydrocarbon group include adamantyl, adamantylmethyl, norbornyl,norbornylmethyl, perfluoroadamantyl and perfluoroadamantylmethyl groups.

In the formula (a4-3), A^(f11) is preferably an ethylene group.

The aliphatic hydrocarbon group for A^(f13) is preferably a C₁ to C₆aliphatic hydrocarbon group, more preferably a C₂ to C₃ aliphatichydrocarbon group.

The aliphatic hydrocarbon group for A^(f14) is preferably a C₃ to C₁₂aliphatic hydrocarbon group, more preferably a C₃ to C₁₀ aliphatichydrocarbon group. Among these, A^(f14) is preferably a group containinga C₃ to C₁₂ alicyclic hydrocarbon group, more preferablycyclopropylmethyl, cyclopentyl, cyclohexyl, norbornyl and adamantylgroups.

Examples of the structural unit represented by formula (a4-2) includestructural units represented by formula (a4-1-1) to formula (a4-1-22).

Examples of the structural unit represented by formula (a4-3) includestructural units represented by formula (a4-1′-1) to formula (a4-1′-22).

Examples of the structural unit (a4) include a structural unitrepresented by formula (a4-4):

wherein R^(f21) represents a hydrogen atom or a methyl group,

A^(f21) represents *—(CH₂)_(j1)—, *—(CH₂)_(j2)—O—(CH₂)_(j3)— or*—(CH₂)_(j4)—CO—O—(CH₂)_(j5)—, where * represents a binding site to anoxygen atom,

j1 to j5 each independently represents an integer of 1 to 6, and

R^(f22) represents a C₁ to C₁₀ hydrocarbon group having a fluorine atom.

Examples of the hydrocarbon group having a fluorine atom for R^(f22)include the same ones as those for R^(f2) in the formula (a4-2). R^(f22)is preferably a C₁ to C₁₀ alkyl group having a fluorine atom or a C₃ toC₁₀ alicyclic hydrocarbon group having a fluorine atom, more preferablya C₁ to C₁₀ alkyl group having a fluorine atom, and still morepreferably a C₁ to C₆ alkyl group having a fluorine atom.

In the formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, morepreferably a methylene group or an ethylene group, and still morepreferably a methylene group.

Examples of the structural unit represented by the formula (a4-4)include the following ones.

When Resin (A1) has the structural unit (a4), the content thereof isusually 1 to 20% by mole, preferably 2 to 15% by mole, and morepreferably 3 to 10% by mole, based on all the structural units of theresin (A1).

The structural unit which has a hydrocarbon group having no acid-labilegroup, which is sometimes referred to as the “structural unit (a5)” mayhave a linear, branched or cyclic hydrocarbon group, preferably analicyclic hydrocarbon group.Examples of the structural unit (a5) include one represented by formula(a5-1):

where R⁵¹ represents a hydrogen atom or a methyl group;R⁵² represents a C3-C18 alicyclic hydrocarbon group, provided that thealicyclic hydrocarbon group has no substituent on the carbon atom bondedto L⁵¹; andL⁵¹ represents a single bond or a C1-C8 alkanediyl group where amethylene group can be replaced by an oxygen atom or carbonyl group.The alicyclic hydrocarbon group represented by R⁵² may be monocyclic orpolycyclic one.Examples of the alicyclic hydrocarbon group include a monocyclichydrocarbon group such as a C3-C18 cycloalkyl group (e.g. a cyclopropylgroup, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group) anda polycyclic alicyclic hydrocarbon group such as an adamantyl group, ora norbornyl group.Examples of the alicyclic hydrocarbon group having a substituent includea 3-hydroxyadamantyl group, and a 3-methyladamantyl group.Examples of the C₁ to C₈ aliphatic hydrocarbon group include an alkylgroup such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octylgroups.

Examples of the alicyclic hydrocarbon group having a substituent for R⁵²include 3-hydroxyadamantyl group and 3-methyladamantyl group.

R⁵² is preferably an unsubstituted C₃ to C₁₈ alicyclic hydrocarbongroup, and more preferably an adamantyl, norbornyl or cyclohexyl group.

Examples of the divalent saturated hydrocarbon group for L⁵¹ include adivalent saturated aliphatic hydrocarbon group and a divalent saturatedalicyclic hydrocarbon group, and a divalent saturated aliphatichydrocarbon group is preferred.

Examples of the divalent saturated aliphatic hydrocarbon group includean alkanediyl group such as methylene, ethylene, propanediyl, butanediyland pentanediyl groups.

Examples of the divalent saturated alicyclic hydrocarbon group includeany of a monocyclic group and a polycyclic group.

Examples of the monocyclic group include cycloalkanediyl group such ascyclopentanediyl and cyclohexanediyl groups. Examples of the polycyclicgroup include adamantanediyl and norbornanediyl groups.

Examples of the saturated hydrocarbon group in which a methylene grouphas been replaced by an oxygen atom or a carbonyl group include groupsrepresented by formula (L1-1) to formula (L1-4). In formula (L1-1) toformula (L1-4), * represents a binding site to an oxygen atom.

In the formulae, X^(X1) represents an oxycarbonyl group or a carbonyloxygroup,

L^(X1) represents a C₁ to C₁₆ divalent saturated aliphatic hydrocarbongroup,

L^(X2) represents a single bond or a C₁ to C₁₅ divalent saturatedaliphatic hydrocarbon group,

provided that the total number of the carbon atoms contained in thegroups of L^(X1) and L^(X2) is 16 or less;

L^(X3) represents a single bond or a C₁ to C₁₇ divalent saturatedaliphatic hydrocarbon group,

L^(X4) represents a single bond or a C₁ to C₁₆ divalent saturatedaliphatic hydrocarbon group,

provided that the total number of the carbon atoms contained in thegroups of L^(X3) and L^(X4) is 17 or less;

L^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L^(X6) and L^(X7) each independently represent a single bond or a C₁ toC₁₄ divalent saturated aliphatic hydrocarbon group,

provided that the total number of the carbon atoms contained in thegroups of L^(X5), L^(X6) and L^(X7) is 15 or less;

L^(X8) and L^(X9) each independently represent a single bond or a C₁ toC₁₂ divalent saturated aliphatic hydrocarbon group,

W^(X1) represents a C₃ to C₁₅ divalent saturated alicyclic hydrocarbongroup,

provided that the total number of the carbon atoms contained in thegroups of L^(X8), L^(X9) and W^(X1) is 15 or less.

L^(X1) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an ethylene group.

L^(X2) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond.

L^(X3) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup.

L^(X4) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X5) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an ethylene group.

L^(X6) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a methylene group or anethylene group.

L^(X7) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X8) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond or amethylene group.

L^(X9) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond or amethylene group.

W^(X1) is preferably a C₃ to C₁₀ divalent saturated alicyclichydrocarbon group, and more preferably a cyclohexanediyl group and anadamantanediyl group.

Examples of the group represented by the formula (L1-1) include thefollowing ones.

Examples of the group represented by the formula (L1-2) include thefollowing ones.

Examples of the group represented by the formula (L1-3) include thefollowing ones.

Examples of the group represented by the formula (L1-4) include thefollowing ones.

L⁵¹ is preferably a single bond, the C₁ to C₈ divalent saturatedhydrocarbon group or the group represented by the formula (L1-1), morepreferably a single bond, the C₁ to C₆ divalent saturated hydrocarbongroup or the group represented by the formula (L1-1).

Examples of the structural unit represented by formula (a5-1) includethe following ones.

Examples of the structural units represented by formula (a5-1) includestructural units represented by the above formulae in which a methylgroup corresponding to R⁵¹ has been replaced by a hydrogen atom.

When the resin (A1) further has the structural unit represented byformula (a5), the content thereof is preferably 1 to 30% by mole, morepreferably 2 to 20% by mole, and still more preferably 3 to 15% by mole,based on all the structural units of the resin.

The resin (A1) is preferably resin which has the structural unit (a1)and the structural unit (s).

In the resin (A1), the structural unit having an acid-labile group ispreferably those represented by formulae (a1-1) and (a1-2), morepreferably those represented by formula (a1-1). The resin (A1) haspreferably at least one of the structural units (a1-1) and (a1-2), morepreferably two or more of the structural units (a1-1) and (a1-2).

For the resin (A1), the structural unit (s) is preferably thoserepresented by formulae (a2) and (a3).

For the resin (A1), the structural unit (a2) is preferably thoserepresented by formula (a2-1). For the resin (A1), the structural unit(a3) is preferably those represented by formulae (a3-1), (a3-2) and(a3-4).

When the resin (A1) has a structural unit derived from a monomer havingan adamantyl group, preferably the structural unit represented byformula (a1-1), the content of the structural unit is preferably 15% ormore by mole based on all of the structural units having an acid-labilegroup. When the photoresist composition has adamantane ring-containingstructural units in larger amount, the photoresist pattern obtainedtherefrom can have more improved resistance to dry-etching.

The resin (A1) can be produced by polymerizing monomers from which astructural unit having an acid-labile group is derived optionally with acompound from which a structural unit having no acid-labile group isderived in a manner of radical polymerization or a known polymerizationmethod.

The weight-average molecular weight of the resin (A1) is usually 2,000or more, preferably 2,500 or more, and more preferably 3,000 or more,and usually 50,000 or less, preferably 30,000 or less, more preferably15,000 or less.

The weight-average molecular weight can be measured with gel permeationchromatography (standard: polyethylene). The detailed method ofmeasurement is described in Examples of the present specification.

The resin (A2) has a structural unit represented by formula (I).

In formula (I), R¹ represents a C1-C13 fluorinated saturated hydrocarbongroup,A¹ represents a single bond, a C1-C6 alkanediyl group, or*-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-, where * represents a binding site to anoxygen atom, A², A³ and A⁴ each independently represent a C₁ to C₆alkanediyl group, X¹ and X² each independently represent —O—, —CO—O— or—O—CO—, “a” represents 0 or 1 and “b” represents 0 or 1, andR² represents a C1-C18 hydrocarbon group.Examples of the fluorinated saturated hydrocarbon group represented byR¹ include a fluoromethyl group, trifluoromethyl group, 1,1-fluoroethylgroup, 2,2-fluoroethyl group, a 2,2,2-trifluoroethyl group, aperfluoroethyl group, a 3,3,3-trifluoro propyl group, a1,1,2,2-tetrafluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a1,1,2,2,3,3-hexafluoropropyl group, a perfluoroethylmethyl group,1-(trifluoromethyl)-2,2,2-trifluoroethyl group,1-(trifluoromethyl)-2,2,3,3,3-pentafluoropropyl group,1-(perfluoroethyl)-2,2,3,3,3-pentafluoropropyl group1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl group, perfluoropropylgroup, 1,1,2,2-tetrafluorobutyl group, 1,1,2,2,3,3-hexafluorobutylgroup, 3,3,4,4,4-pentafluorobutyl group, 2,2,3,3,4,4,4-heptafluorobutylgroup, 1,1,2,2,3,3,4,4-octafluorobutyl group, a perfluorobutyl group, a1,1-bis(trifluoro)methyl-2,2,2-trifluoroethyl group,2-(perfluoropropyl)ethyl group, 2,2,3,3,4,4,5,5,5-nonabisfluoropentylgroup, 3,3,4,4,5,5,5-heptafluoropentyl group,1,1,2,2,3,3,4,4-octafluoropentyl group, a perfluoropentyl group,1,1,2,2,3,3,4,4,5,5-fluorodecapentyl group,1,1-(trifluoromethyl)-2,2,3,3,3-pentafluoropropyl group, aperfluoropentyl group, a 2-(perfluorobutyl)ethyl group, a1,1,2,2,3,3,4,4,5,5-decafluorohexyl group,3,3,4,4,5,5,6,6,6-nonafluorohexyl group,2,2,3,3,4,4,5,5,6,6,6-undecafluorohexyl group,1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl group, a perfluoropentylmethylgroup, a perfluorohexyl group, a perfluorocyclohexyl group and aperfluoroadamantyl group.R¹ is preferably a C1-C13 fluorinated alkyl group, more preferably—(CH₂)_(n)—Rf or —CH(Rf1)(Rf2), where “n” represents an integer of 0 to6, and Rf, Rf1 and Rf2 each independently represent a C1-C6perfluoroalkyl group.“n” is preferably an integer of 0 to 4, more preferably an integer of 0to 3, and still more preferably an integer of 0 to 2.Rf is preferably a C1-C4 perfluoroalkyl group, more preferably a C2-C4perfluoroalkyl group, and still more preferably a C3-C4 perfluoroalkylgroup.Rf1 and Rf2 are each independently preferably a C1-C4 perfluoroalkylgroup, more preferably a C1-C3 perfluoroalkyl group, and still morepreferably a C1-C2 perfluoroalkyl group.R¹ is more preferably a C1-C4 perfluoroalkyl group, —CH₂—Rf′,—(CH₂)₂—Rf′, or —CH(CF₃)(CF₃). Rf′ represents a C1-C4 perfluoroalkylgroup.Examples of the alkanediyl group represented by A¹, A², A³ and A⁴include a linear alkanediyl group such as a methyl group, an ethylenegroup, a propane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl group and hexane-1,6-diyl group, and a branchedalkanediyl group such as an ethane-1,1-diyl group, a propane-1,2-diylgroup, a butane-1,3-diyl group, a 2-methy propane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and2-methylbutane-1,4-diyl group.Examples of *-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)- include *-A²-O—, *-A²-CO—O—,*-A²-CO—O-A⁴-, *-A²-O—CO—, *-A²-CO—O-A³-CO—O—, *-A²-CO—O-A³-CO—O-A⁴-,*-A²-O—CO-A³-O—, *-A²-O-A³-CO—O—, *-A²-CO—O-A³-O—CO— and*-A²-O—CO-A³-O—CO—, preferably -A²-O— and *-A²-CO—O—.Preferably, A², A³ and A⁴ are each independently a C2-C6 alkanediylgroup.A¹ is preferably a single bond or -A²-X¹—, more preferably a single bondor -A²-CO—O—, and still more preferably a single bond.Examples of the hydrocarbon group represented by R² include an alkylgroup, an alicyclic hydrocarbon group, an aromatic hydrocarbon group andany combination of them.Examples of the alkyl group for R² include a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, aheptyl group and an octyl group.The alicyclic hydrocarbon group represented by R² may be monocyclic orpolycyclic. Examples of monocyclic one include a cycloalkyl group suchas a cyclopentyl group, a cyclohexyl group, a cycloheptyl group and acyclooctyl group. Examples of polycyclic one include a dacahydronaphtylgroup, an adamantyl group and a norbornyl group. Examples of a groupcomposed of an alkyl group and an alicyclic hydrocarbon group include amethylcyclohexyl group, a dimethylcyclohexyl group, amethylnorbornylgroup, cyclohexylmethyl group, an adamantylmethyl group, and anorbornylethyl group.

Examples of the aromatic hydrocarbon group for R² include a phenylgroup, a naphthyl group, an anthryl group, a p-methylphenyl group, ap-tert-butylphenyl group, p-adamantylphenyl group, a tolyl group, axylyl group, a cumenyl group, a mesityl group, a biphenyl group, aphenanthryl group, a 2,6-diethylphenyl group, and 2-methyl-6-ethylphenylgroup.

R² is preferably a C3-C6 branched alkyl group, a C5-C8 cycloalkyl groupand an adamantyl group, and more preferably an isopropyl group, acyclohexyl group and an adamantyl group.Examples of the structural unit represented by formula (I) include thefollowing ones.

The structural unit represented by formula (I) can be derived from acompound represented by formula (I′);

where R¹, R² and A¹ are as defined above.The compound represented by formula (I′) can be obtained by reacting acompound represented by formula (I′-a) with a compound represented byformula (I′-b) in presence of an acid catalyst, such as a sulfuric acid,in a solvent such as 1-chlorobutane or toluene:

wherein R¹, R² and A¹ are as defined above.

The reaction is preferably conducted at temperature of preferably 20° C.to 120° C., for 0.5 to 24 hours.

Examples of the compound represented by the formula (I′-a) includecompounds represented by formulae below which are available on themarket.

The compound represented by formula (I′-b) can be obtained by reacting acompound represented by formula (I′-c) with an acid catalyst, such astrifluoromethansulfonic acid, in a solvent such as chloroform, attemperature of preferably 20° C. to 120° C., for 0.5 to 24 hours:

wherein R² is as defined above.

The compound represented by formula (I′-c) can be obtained by reacting acompound represented by formula (I′-d) with a compound represented byformula (I′-e) in presence of a basic catalyst, such as pyridine, in asolvent such as chloroform, at temperature of preferably 5° C. to 80°C., for 0.5 to 48 hours:

wherein R² is as defined above.Examples of the compound represented by the formula (I′-e) includecompounds represented by formulae below which are available on themarket.

In the resin (A2), the content of the structural unit represented byformula (I) is preferably 10 to 100% by mole, more preferably 50 to 100%by mole, and still more preferably 80 to 100% by mole, based on all thestructural units of the resin (A2). The resin (A2) which consists of thestructural unit represented by formula (I) is furthermore preferredaccording to the photoresist composition of the disclosure.The resin (A2) may further have another structural unit such as thestructural unit (a1), the structural unit (s), the structural unit (t).When the resin (A2) may further have another structural unit, the resin(A2) preferably has the structural unit represented by formula (I) andthe structural unit (t), more preferably has the structural unitrepresented by formula (I) and the structural unit (a5).The resin (A2) can be produced by polymerizing the compound representedby formula (I′), optionally with another monomer in a manner of radicalpolymerization or a known polymerization method.The weight average molecular weight of the resin (A2) is preferably 6000or more, and more preferably 7,000 or more, and preferably 80,000 orless, and more preferably 60,000 or less.In the photoresist composition of the disclosure, the amount of theresin (A2) is preferably 1 to 60 weight parts, more preferably 2 to 50weight parts, still more preferably 3 to 40 weight parts, and furthermore preferably 4 to 30 weight parts, relative to 100 parts of the resin(A1).

The photoresist composition of the disclosure usually contains 80% byweight or more of the resin (A1) and resin (A2) in total, based on sumof solid components. The photoresist composition of the disclosureusually contains 99.9% by mass or less of the resins in total, based onsum of solid components. In this specification, “solid components” meanscomponents other than solvent in the photoresist composition. The amountcan be measured with a known analysis equipment such as gas or liquidchromatography.

The photoresist composition of the disclosure may further containanother resin than the resins (A1) and (A2). Examples of such anotherresin include those consisting of the structural units selected from thestructural units (a2), (a3), (a4) and (a5).

The photoresist composition contains an acid generator.

The acid generator is a compound which can be decomposed by light orradiation to generate an acid. The acid generators may be either ionicor non-ionic one. The acid generator can be used singly or incombination of two or more of them.

The non-ionic acid generator includes organic halide, sulfonate esters(e.g., 2-nitrobenzylester, aromatic sulfonate, oxime sulfonate,N-sulfonyloxyimide, sulfonyl oxyketone, diazonaphthoquinone 4-sulfonate)and sulfone (e.g., disulfone, ketosulfone, sulfonyldiazomethane). Theionic acid generator includes an onium salt comprising an onium cation(e.g., a diazonium salt, a phosphonium salt, a sulfonium salt, aniodonium salt). Anions of the onium salts include a sulfonic acid anion,a sulfonylimide anion and a sulfonylmethide anion.

The acid generator includes compounds which generate an acid uponradiation, which are described in JP63-26653A1, JP55-164824A1,JP62-69263A1, JP63-146038A1, JP63-163452A1, JP 62-153853A1,JP63-146029A1, U.S. Pat. No. 3,779,778, U.S. Pat. No. 3,849,137, Germanpatent No. 3914407 and European patent No. 126712.

The acid generator is preferably a fluorine-containing acid generator,more preferably a salt represented by formula (B1):

wherein Q¹ and Q² each independently represent a fluorine atom or aC1-C6 perfluoroalkyl group,L^(b1) represents a single bond or a C1-C24 divalent saturatedhydrocarbon group where a methylene group can be replaced by an oxygenatom or a carbonyl group and where a hydrogen atom can be replaced by anfluorine atom or a hydroxy group,Y represents a methyl group or a C3-C18 alicyclic hydrocarbon groupwhere a methylene group can be replaced by an oxygen atom, a sulfonylgroup or a carbonyl group and where a hydrogen atom can be replaced by asubstituent, andZ⁺ represents an organic cation.

Examples of the perfluoroalkyl group represented by Q¹ and Q² include atrifluoromethyl group, a pentafluoroethyl group, a heptafluoropropylgroup, a nonafluorobutyl group, an undecafluoropentyl group and atridecafluorohexyl group. It is preferred that Q¹ and Q² eachindependently represent a fluorine atom or a trifluoromethyl group, andit is more preferred that Q¹ and Q² are fluorine atoms.

Examples of the divalent saturated hydrocarbon group represented byL^(b1) include linear alkanediyl groups, branched chain alkanediylgroups, a monocyclic divalent alicyclic hydrocarbon group, a polycyclicdivalent alicyclic hydrocarbon group and combinations of them.Specific examples of them includelinear alkanediyl groups such as a methylene group, an ethylene group, apropane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1, 6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup;branched chain alkanediyl groups including a group formed by attaching aside chain to a linear alkanediyl group, such as a butan-1,3-diyl group,a2-methylpropane-1, 3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group, and a 2-methylbutane-1,4-diyl group;a monocyclic divalent alicyclic hydrocarbon group such as acyclobutan-1,3-diyl group, cyclopentane-1,3-diyl group, acyclohexane-1,2-diyl group, a 1-methylcyclohexane-1,2-diyl group,cyclohexane-1,4-diyl group, cyclooctane-1,2-diyl group, and acyclooctane-1,5-diyl group; anda polycyclic divalent alicyclic hydrocarbon group such as anorbornane-2,3-diyl group, norbornane-1,4-diyl group, anorbornane-2,5-diyl group, an amadantane-1,2-diyl group, anamadantane-1,5-diyl group and an amadantane-1,6-diyl group.When L^(b1) represents a divalent saturated hydrocarbon group in which amethylene group has been replaced by an oxygen atom or a carbonyl group,examples of L^(b1) include the moiety represented by any one of formulae(b1-1) to (b1-3) as follow;

wherein L^(b2) represents a single bond or a C1-C22 divalent saturatedhydrocarbon group in which a hydrogen atom can be replaced by a fluorineatom, andL^(b3) represents a single bond or a C1-C22 divalent saturatedhydrocarbon group in which a hydrogen atom can be replaced by a fluorineatom or a hydroxyl group and in which a methylene group can be replacedby an oxygen atom or a carbonyl group, provided that the total number ofthe carbon atoms in L^(b2) and L^(b3) is up to 22;L^(b4) represents a single bond or a C1-C22 divalent saturatedhydrocarbon group in which a hydrogen atom can be replaced by a fluorineatom, and L^(b5) represents a single bond or a C1-C22 divalent saturatedhydrocarbon group in which a hydrogen atom can be replaced by a fluorineatom or a hydroxyl group and in which a methylene group can be replacedby an oxygen atom or a carbonyl group, provided that the total number ofthe carbon atoms in L^(b4) and L^(b5) is up to 22;L^(b6) represents a C1-C15 divalent saturated hydrocarbon group in whicha hydrogen atom can be replaced by a fluorine atom or a hydroxyl group,and L^(b7) represents a single bond or a C1-C15 divalent saturatedhydrocarbon group in which a hydrogen atom can be replaced by a fluorineatom or a hydroxyl group and in which a methylene group can be replacedby an oxygen atom or a carbonyl group, provided that the total number ofthe carbon atoms in L^(b6) and L^(b7) is up to 23; and * represents abinding site to Y.In formula (b1-1) to formula (b1-3), when a methylene group has beenreplaced by an oxygen atom or a carbonyl group, the carbon number of thesaturated hydrocarbon group corresponds to the number of the carbon atombefore replacement.Examples of the divalent saturated hydrocarbon group are the sameexamples as the divalent saturated hydrocarbon group of L^(b1).L^(b2) is preferably a single bond.L^(b3) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.L^(b4) is preferably a C₁ to C₈ divalent saturated hydrocarbon groupwhere a hydrogen atom may be replaced by a fluorine atom.L^(b5) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.L^(b6) is preferably a single bond or a C₁ to C₄ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom.L^(b7) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and where a methylene group may be replaced byan oxygen atom or a carbonyl group.Among these, the group represented by the formula (b1-1) or the formula(b1-3) is preferred.Examples of the divalent group represented by the formula (b1-1) includethe following groups represented by formula (b1-4) to formula (b1-8):

wherein L^(b8) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom or a hydroxy group;L^(b9) represents a C₁ to C₂₀ divalent saturated hydrocarbon group, andL^(b10) represents a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, provided that the total number of carbon atomscontained in the group of L^(b9) and L^(b10) is 20 or less;L^(b11) represents a C₁ to C₂₁ divalent saturated hydrocarbon group, andL^(b12) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, provided that the total number of carbon atomscontained in the group of L^(b11) and L^(b12) is 21 or less;L^(b13) represents a C₁ to C₁₉ divalent saturated hydrocarbon group,L^(b14) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group, and L^(b15) represents a single bond or a C₁ to C₁₈divalent saturated hydrocarbon group where a hydrogen atom may bereplaced by a fluorine atom or a hydroxy group, provided that the totalnumber of carbon atoms contained in the group of L^(b13),L^(b14) and L^(b15) is 19 or less;L^(b16) represents a C₁ to C₁₈ divalent saturated hydrocarbon group,L^(b17) represents a C₁ to C₁₈ divalent saturated hydrocarbon group, andL^(b18) represents a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, provided that the total number of carbon atomscontained in the group of L^(b16), L^(b17) and L^(b18) is 19 or less;and * represents a binding site to Y.L^(b8) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.L^(b9) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.L^(b10) is preferably a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.L^(b11) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.L^(b12) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.L^(b13) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.L^(b14) is preferably a single bond or a C₁ to C₆ divalent saturatedhydrocarbon group.L^(b15) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.L^(b16) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.L^(b17) is preferably a C₁ to C₆ divalent saturated hydrocarbon group.L^(b18) is preferably a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₄divalent saturated hydrocarbon group.Examples of the divalent group represented by the formula (b1-3) includethe following groups represented by formula (b1-9) to formula (b1-11):

wherein L^(b19) represents a single bond or a C₁ to C₂₃ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom, and L^(b20) represent a single bond or a C₁ to C₂₃divalent saturated hydrocarbon group where a hydrogen atom may bereplaced by a fluorine atom, a hydroxy group or an acyloxy group, and amethylene group contained in an acyloxy group may be replaced by anoxygen atom or a carbonyl group, and a hydrogen atom contained in anacyloxy group may be replaced by a hydroxy group, provided that thetotal number of carbon atoms contained in the group of L^(b19) andL^(b20) is 23 or less;L^(b21) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, L^(b22) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group, and L^(b23) represents a single bond or a C₁ to C₂₁divalent saturated hydrocarbon group where a hydrogen atom may bereplaced by a fluorine atom, a hydroxy group or an acyloxy group, and amethylene group contained in an acyloxy group may be replaced by anoxygen atom or a carbonyl group, and a hydrogen atom contained in anacyloxy group may be replaced by a hydroxy group, provided that thetotal number of carbon atoms contained in the group of L^(b21), L^(b22)and L^(b23) is 21 or less;L^(b24) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, L^(b25) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group, and L^(b26) represents a single bond or a C₁ to C₂₀divalent saturated hydrocarbon group where a hydrogen atom may bereplaced by a fluorine atom, a hydroxy group or an acyloxy group, and amethylene group contained in an acyloxy group may be replaced by anoxygen atom or a carbonyl group, and a hydrogen atom contained in anacyloxy group may be replaced by a hydroxy group, provided that thetotal number of carbon atoms contained in the group of L^(b24), L^(b25)and L^(b26) is 21 or less;and * represents a binding site to Y.In formula (b1-9) to formula (b1-11), when a hydrogen atom has beenreplaced by an acyloxy group, the carbon number of the saturatedhydrocarbon group corresponds to the number of the carbon atom, CO and Oin addition to the carbon number of the saturated hydrocarbon group.

Examples of the acyloxy group include acetyloxy, propionyloxy,butyryloxy, cyclohexyl carbonyloxy and adamantyl carbonyloxy groups.

Examples of the acyloxy group having a substituent include oxoadamantylcarbonyloxy, hydroxyadamantyl carbonyloxy, oxocyclohexyl carbonyloxy andhydroxycyclohexyl carbonyloxy groups.

Examples of the group represented by the formula (b1-4) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-5) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-6) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-7) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-8) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-2) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-9) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-10) include thefollowing ones:

where * represents a binding site to Y.Examples of the group represented by the formula (b1-11) include thefollowing ones:

where * represents a binding site to Y.Examples of the alicyclic hydrocarbon group represented by Y includethose represented by formulae (Y1) to (Y11).Examples of the alicyclic hydrocarbon group represented by Y, in which amethylene group can be replaced by an oxygen atom, a sulfonyl group or acarbonyl group, include those represented by formulae (Y12) to (Y27).

Among them, preferred are those represented by formulae (Y1) to (Y20),more preferred are those represented by formulae (Y11), (Y15), (Y16) and(Y20), and still more preferred are those represented by formulae (Y11)and (Y15).

Examples of the substituents for the alicyclic hydrocarbon grouprepresented by Y include a halogen atom, a hydroxy group, an oxo group,a C1-C12 alkyl group, a C1-C12 hydroxy-containing alkyl group, a C3-C16alicyclic hydrocarbon group,

a C1-C12 alkoxy group, a C6-C18 aromatic hydrocarbon group optionallysubstituted with a C1-C4 alkyl group, a C7-C21 aralkyl group, a C2-C4acyl group, a glycidyloxy group, or —(CH₂)_(j2)—O—CO—R_(b1) group whereR_(b1) represents a C1-C16 alkyl group, a C3-C16 alicyclic hydrocarbongroup, or a C6-C18 aromatic hydrocarbon group optionally substitutedwith a C1-C4 alkyl group. The symbol j2 represents an integer of 0 to 4.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.Examples of the hydroxyl-containing methyl group include a hydroxymethylgroup and a hydroxyethyl group.Examples of alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup.Examples of an aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an antolyl group, a p-methylphenylgroup, p-tert-butylphenyl group, p-adamantylphenyl group, a tolyl group,a xylyl group, a cumenyl group, a mesityl group, a biphenyl group, aphenanthryl group, a 2,6-diethylphenyl group, 2-methyl-6-ethylphenylgroup.Examples of an aralkyl group include a benzyl group, a phenethyl group,a phenylpropyl group, a naphthylmethyl group and a naphthylethyl group.Examples of an acyl group include an acetyl group, a propionyl group anda butyryl group.Examples of the group represented by Y include the following ones.

Y is preferably a C3-C18 alicyclic hydrocarbon group which can have asubstituent, more preferably an adamantyl group which can have asubstituent such as oxo group or a hydroxyl group, more preferably anadamantyl group, a hydroxyadamantyl group, or an oxoadamantyl group.Examples of the sulfonic acid anion of the salt represented by formula(B1) include an anion represented by formulae (B1-A-1) to (B1-A-33), andmore preferably an anions represented by formula (B1-A-1) to formula(B1-A-4), formula (B1-A-9), formula (B1-A-10), formula (B1-A-24) toformula (B1-A-33).

In formula (B1-A-1) to formula (B1-A-33), R^(i2) to R^(i7) eachindependently represent a C₁ to C₄ alkyl group, and preferably a methylgroup or an ethyl group, R^(i8) represent a C₁ to C₁₂ aliphatichydrocarbon group, preferably a C₁ to C₄ alkyl group, a C₅ to C₁₂monovalent alicyclic hydrocarbon group or a group composed of the alkylgroup and the alicyclic hydrocarbon group, more preferably a methylgroup, an ethyl group, a cyclohexyl group or an adamantyl group. L⁴represents a single bond or a C₁ to C₄ alkanediyl group. Q¹ and Q²represent the same meaning as defined above.

Specific examples of the anion for the salt represented by formula (B1)include JP2010-204646A1.

Among these, preferred examples of the sulfonic acid anion for the saltrepresented by the formula (B1) include anions represented by formulae(B1a-1) to (B1a-15).

Preferred examples of the sulfonic acid anion include anions representedby the formulae (B1a-1) to (B1a-3) and (B1a-7) to (B1a-15).Examples of the organic cation represented by Z⁺ include an organiconium cation such as an organic sulfonium cation, an organic iodoniumcation, an organic ammonium cation, a benzothiazolium cation and anorganic phosphonium cation. As Z⁺, an organic sulfonium cation and anorganic iodonium cation are preferred, and an arylsulfonium cation ismore preferred. Herein, the arylsulfonium includes those having one, twoor three aryl groups.Preferable examples of the organic cation represented by Z⁺ include theorganic cations represented by the formulae (b2-1) to (b2-4):

wherein R^(b4), R^(b5) and R^(b6) independently represent a C1-C30aliphatic hydrocarbon group in which a hydrogen atom can be replaced bya hydroxy group, a C1-C12 alkoxy group or a C6-C18 alicyclic hydrocarbongroup,a C3-C36 alicyclic hydrocarbon group in which a hydrogen atom can bereplaced by a halogen atom, a C2-C4 acyl group or a glycidyloxy group,anda C6-C36 aromatic hydrocarbon group in which a hydrogen atom can bereplaced by a halogen atom, a hydroxy group, or C1-C12 alkoxy group; andR^(b4) and R^(b5), R^(b4) and R^(b6), or R^(b5) and R^(b6) can be bondedeach other to form a ring containing S⁺;R^(b7) and R^(b8) are independently in each occurrence a hydroxy group,a C1-C12 alkyl group or a C1-C12 alkoxy group;m2 and n2 independently represents an integer of 0 to 5;R^(b9) and R^(b10) independently represent a C1-C36 aliphatichydrocarbon group or a C3-C36 alicyclic hydrocarbon group, or R^(b9) andR^(b10) are bonded each other to form a ring together with the adjacent—S⁺—, and one or more —CH₂— in the ring may be replaced by an oxygenatom, sulfur atom or carbonyl group; and R^(b11) represents a hydrogenatom, a C1-C36 aliphatic hydrocarbon group, a C3-C36 alicyclichydrocarbon group, or a C6-C18 aromatic hydrocarbon group, and R^(b12)represents a C1-C12 aliphatic hydrocarbon group where a hydrogen atomcan be replaced by a C6-C18 aromatic hydrocarbon group, a C3-C18alicyclic hydrocarbon group, and a C6-C18 aromatic hydrocarbon groupoptionally substituted with C1-C12 alkoxy group or C1-C12alkylcarbonyloxy group;or R^(b11) and R^(b12) are bonded each other to form a C1-C10 divalentacyclic hydrocarbon group which forms a 2-oxocycloalkyl group togetherwith the adjacent —CHCO—, and one or more —CH₂— in the group may bereplaced by an oxygen atom, sulfur atom or carbonyl group; andR^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) independentlyrepresent a hydroxy group, a C1-C12 alkyl group or a C1-C12 alkoxygroup;L^(b31) represents —S— or —O—; ando2, p2, s2 and t2 each independently represents an integer of 0 to 5;q2 and r2 each independently represents an integer of 0 to 4; and u2represents 0 or 1.

Examples of the aliphatic hydrocarbon group represented by eachsubstituent include an alkyl group such as a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group, a hexyl group, an octylgroup, and a 2-ethylhexyl group. The aliphatic hydrocarbon grouprepresented by R^(b9) to R^(b12) is preferably a C1-C18 alkyl group,more preferably a C1-C12 alkyl group.

Examples of the alkyl group where a hydrogen atom has been replaced byan alicyclic hydrocarbon group include 1-(adamantane-1-yl) alkane-1-ylgroup.The alicyclic hydrocarbon group represented by each substituent may bemonocyclic or polycyclic, a hydrogen atom of which can be replaced by analkyl group. When a hydrogen atom of it has been replaced by an alkylgroup, the total number of carbon atoms is 30 or less.Examples of the monocyclic alicyclic hydrocarbon group include acycloalkyl group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclodecylgroup.Examples of the polycyclic alicyclic hydrocarbon group include adecahydronaphtyl group, an adamantyl group, a nobornyl group, and thefollowing ones.

The alicyclic hydrocarbon group represented by R^(b9) to R^(b12) haspreferably 3 to 18, more preferably 4 to 12, carbon atoms. Examples ofthe alicyclic hydrocarbon group where a hydrogen atom has been replacedby an alkyl group include a methylcyclohexyl group, a2-alkyladamantane-2-yl group, a methylnorbornyl group, and an isobornylgroup.Preferable examples of the aromatic hydrocarbon group includesubstituted or unsubstituted phenyl group such as a phenyl group, atolyl group, a xylyl group, a cumenyl group, a mesityl group, a4-ethylphenyl group, 4-tert-butylphenyl group, 4-cyclohexylphenyl group,a 4-adamantylphenyl group, a 2, 6-diethylphenyl group, a2-methyl-6-ethylphenyl group; a biphenyl group, a naphtyl group, aphenanthryl group.Preferable examples of the aromatic hydrocarbon group where a hydrogenatom has been replaced by an alkoxy group include 4-methoxyphenyl group.Preferable examples of the alkyl group where a hydrogen atom has beenreplaced by an aromatic hydrocarbon group, i.e., an aralkyl group,include a benzyl group, a phenethyl group, a phenylpropyl group, atrityl group, a naphthylmethyl group and a naphthylethyl group.When the aromatic hydrocarbon group has an alkyl group or an alicyclichydrocarbon group as a substituent, the substituent is preferably aC1-C12 alkyl group or a C3-C18 alicyclic hydrocarbon group. Examples ofthe alkoxy group include a methoxy group, an ethoxy group, a propoxygroup, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxygroup, an octyloxy group, a decyloxy group and a dodecyloxy group.Examples of the C2-C4 acyl group include an acetyl group, a propyonylgroup and a butyryl group.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.Preferable examples of the alkylcarbonyloxy group include amethylcarbonyloxy group, an ethylcarbonyloxy group, n-propylcarbonyloxygroup, an isopropylcarbonyloxy group, n-butylcarbonyloxy group,sec-butylcarbonyloxy group, a tert-butylcarbonyloxy group, apentylcarbonyloxy group, a hexylcarbonyloxy group, an octylcarbonyloxygroup and 2-ethyl hexylcarbonyloxy group.

The ring containing S⁺ formed by bonding R^(b4) and R^(b5), R^(b4) andR^(b6) or R^(b5) and R^(b6) each other may be a monocyclic ring, apolycyclic ring, an aromatic ring, a non-aromatic ring, a saturated ringor a unsaturated ring. The ring can contain a sulfur atom or oxygen atomin addition to S. The ring preferably has 3 to 18 carbon atoms, and morepreferably has 4 to 13 carbon atoms. Examples of such ring include, 3 to12-membered rings, preferably 3 to 7-membered rings, specifically thefollowing ones.

Examples of the ring group formed by bonding R^(b9) and R^(b10) togetherwith the adjacent S⁺ and the divalent acyclic hydrocarbon group include,3 to 12-membered rings, preferably 3 to 7-membered rings, specifically athiolan-1-ium ring (tetrahydrothiphenium ring), a thian-1-ium ring and a1,4-oxathian-4-ium ring.Examples of the ring group formed by bonding R^(b11) and R^(b12) include3 to 12-membered rings, preferably 3 to 7-membered rings, specificallyoxocyclopentane ring, oxocyclohexane ring, oxonorbornane ring andoxoamadantane ring.Among the above-mentioned cations, preferred is the cation representedby the formula (b2-1).Examples of the cation represented by the formula (b2-1) include thefollowing ones.

Examples of the cation represented by the formula (b2-2) include thefollowing ones.

Examples of the cation represented by the formula (b2-3) include thefollowing ones.

Examples of the cation represented by the formula (b2-4) include thefollowing ones.

The acid generator for the photoresist composition of the disclosure ispreferably those having an anion represented by any one of the formulae(B1a-1) to (B1a-3) and (B1a-7) to (B1a-15) and a cation represented byany one of the formulae (b2-1) and (b2-3).The acid generator is preferably those represented by formulae (B1-1) to(B1-30), more preferably those having an arylsulfonium cation, that isthose represented by formulae (B1-1), (B1-2), (B1-3), (B1-5), (B1-6),(B1-7), (B1-11), (B1-12), (B1-13), (B1-17), (B1-20), (B1-21), (B1-22),(B1-23), (B1-24), (B1-25), (B1-26) and (B1-29).

The amount of the acid generator represented by formula (B1) ispreferably 30% by mass or more, and 100% by mass or less, morepreferably 50% by mass or more, and 100% by mass or less, and still morepreferably substantially 100% by weight with respect to 100% by mass oftotal acid generator.

The amount of the acid generator is preferably 1 weight parts or more,more preferably 3 weight parts or more, and preferably 30 weight partsor less, and more preferably 25 weight parts or less relative to 100weight parts of the resin (A1).

The photoresist compositions of the disclosure may further contain asolvent.

The amount of the solvent is usually 90% by weight or more, preferably92% by weight or more preferably 94% by weight or more based on totalamount of the photoresist composition of the disclosure. The amount ofthe solvent is usually 99.9% by weight or less and preferably 99% byweight or less based on total amount of the photoresist composition ofthe disclosure.

Examples of the solvent include a glycoletherester such asethylcellosolve acetate, methylcellosolve acetate andpropyleneglycolmonomethylether acetate; an ester such as ethyl lactate,butyl acetate, amyl acetate and ethyl pyruvate; a ketone such asacetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; and acyclic ester such as γ-butyrolactone.

The photoresist compositions of the disclosure may further contain aquencher. The “quencher” has the property that it can trap an acid,especially an acid generated from the acid generator by applying aradiation.

Examples of the quencher include a basic nitrogen-containing organiccompound and a weak acid salt.

Examples of the basic nitrogen-containing organic compound include anamine compound such as an aliphatic amine, an aromatic amine and anammonium salt. Examples of the aliphatic amine include a primary amine,a secondary amine and a tertiary amine. Examples of the aromatic amineinclude an aromatic amine in which an aromatic ring has an amino groupsuch as aniline and a heteroaromatic amine such as pyridine.

Examples of the quencher include 1-naphthylamine, 2-naphthylamine,aniline, diisopropylaniline, 2-,3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,pentylamine, dioctylamine, triethylamine, trimethylamine,tripropylamine, tributylamine, tripentylamine, trihexylamine,triheptylamine, trioctylamine, trinonylamine, tridecylamine,methyldibutylamine, methyldipentylamine, methyldihexylamine,methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine,methyldinonylamine, methyldidecylamine, ethyldibutylamine,ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine,ethyldioctylamine, ethyldinonylamine, ethyldidecylamine,dicyclohexylmethylamine, 2 tris [2-(2-methoxyethoxy)ethyl]amine,triisopropanolamine, ethylenediamine, tetramethylenediamine,hexamethylenediamine, 4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenyl methane, piperazine, morpholine,piperidine, hindered amine compound having a piperidine structure,2,2′-methylenebisaniline, imidazole, 4-methylimidazole, pyridine,4-methylpyridine, 1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene, 1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane, di(2-pyridyl)ketone, 4,4′-dipyridylsulfide, 4,4′-dipyridyl disulfide, 2,2′-dipyridylamine,2,2′-dipicolylamine and bipyridine.

Examples of the quaternary ammonium salts include tetramethylammoniumhydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide,tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide,(3-trifluoromethylphenyl)trimethylammonium hydroxide and(2-hydroxyethyl)trimethylammonium hydroxide (so-called “choline”).

The weak acid salt is usually lower in acidity than the acid generatoras mentioned above and Salt (I), examples of which include carboxylicacid salts and sulfonic acid salts.

The acidity in the weak acid salt is shown by the acid dissociationconstant (pKa).

The acid dissociation constant of acid generated from the weak acid saltis usually salt of −3<pKa.

The weak acid salt is preferably a salt of −1<pKa<7, and more preferablya salt of 0<pKa<5.

Specific examples of the weak acid salt include the following ones.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlyrepresent a C₁ to C₁₂ hydrocarbon group, a C₁ to C₆ alkoxyl group, a C₂to C₇ acyl group, a C₂ to C₇ acyloxy group, a C₂ to C₇ alkoxycarbonylgroup, a nitro group or a halogen atom;

m′ and n′ each independently represent an integer of 0 to 4.

Examples of the hydrocarbon group for R^(D1) and R^(D2) include any ofan aliphatic hydrocarbon group, an alicyclic hydrocarbon group, anaromatic hydrocarbon group and a combination thereof.

Examples of the aliphatic hydrocarbon group include an alkyl group suchas methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl,pentyl, hexyl and nonyl groups.

The alicyclic hydrocarbon group is any one of monocyclic or polycyclichydrocarbon group, and saturated or unsaturated hydrocarbon group.Examples thereof include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl and cyclododecyl groups;adamantyl and norbornyl groups.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, 1-naphthyl, 2-naphthyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl,4-butylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl,anthryl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the combination thereof include an alkyl-cycloalkyl group, acycloalkyl-alkyl group and an aralkyl group (e.g., phenylmethyl,1-phenylethyl, 2-phenylethyl, 1-phenyl-1-propyl, 1-phenyl-2-propyl,2-phenyl-2-propyl, 3-phenyl-1-propyl, 4-phenyl-1-butyl,5-phenyl-1-pentyl and 6-phenyl-1-hexyl groups).

Examples of the alkoxyl group include methoxy and ethoxy groups.

Examples of the acyl group include acetyl, propanonyl, benzoyl andcyclohexanecarbonyl groups.

Examples of the acyloxy group include a group in which oxy group (—O—)bonds to an acyl group.

Examples of the alkoxycarbonyl group include a group in which thecarbonyl group (—CO—) bonds to the alkoxy group.

Example of the halogen atom is a chlorine atom, a fluorine atom andbromine atom.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlypreferably represent a C₁ to C₈ alkyl group, a C₃ to C₁₀ cycloalkylgroup, a C₁ to C₆ alkoxyl group, a C₂ to C₄ acyl group, a C₂ to C₄acyloxy group, a C₂ to C₄ alkoxycarbonyl group, a nitro group or ahalogen atom.

m′ and n′ independently preferably represent an integer of 0 to 3, morepreferably an integer of 0 to 2, and more preferably 0.

Specific examples of the salt of the formula (D) include compoundsbelow.

The amount of quencher is preferably 0.01 to 5% by mass, more preferably0.01 to 4% by mass, and still more preferably 0.01 to 3% by mass, basedon sum of the solid components.

The photoresist compositions of the disclosure can contain, ifnecessary, a small amount of various additives such as a sensitizer, adissolution inhibitor, other polymers, a surfactant, a stabilizer and adye as long as the effect of the disclosure is not prevented.

The photoresist compositions of the disclosure can usually be preparedby mixing, in a solvent, resin (A1), resin (A2), an acid generator, andif necessary a quencher and/or additives at a suitable ratio for thecomposition, optionally followed by filtrating the mixture with a filterhaving 0.003 μm to 0.2 μm of a pore size.

The order of mixing these components is not limited to any specificorder. The temperature at mixing the components is usually 10 to 40° C.,which can be selected in view of the resin or the like.

The mixing time is usually 0.5 to 24 hours, which can be selected inview of the temperature. The means for mixing the components is notlimited to specific one. The components can be mixed by being stirred.

The amounts of the components in the photoresist compositions can beadjusted by selecting the amount to be used for production of them.

The photoresist compositions of the disclosure are useful for achemically amplified photoresist composition.

A photoresist pattern can be produced using the photoresist compositionof the disclosure by the following steps (1) to (5):

(1) a step of applying the photoresist composition of the disclosure ona substrate,

(2) a step of forming a composition film by drying the composition,

(3) a step of exposing the composition film to radiation,

(4) a step of baking the exposed composition film, and

(5) a step of developing the baked composition film to form thephotoresist pattern.

The applying of the photoresist composition on a substrate is usuallyconducted using a conventional apparatus such as spin coater. Examplesof the substrate include a silicon wafer or other inorganic material.The substrate may be coated with a reflect-preventing layer such as onecontaining hexamethyldisilazane. For forming the reflect-preventinglayer, such composition for organic reflect-preventing layer asavailable on the market can be used.

The composition film is usually formed by heating the coat layer with aheating apparatus such as hot plate or a decompressor, to thereby dryoff the solvent. The heating temperature is preferably 50 to 200° C.,the time of heating is preferably 10 to 180 seconds, and the operationpressure is preferably 1 to 1.0*10⁵ Pa. These conditions can be selectedin view of the solvent.

The composition film obtained is exposed to radiation using an exposuresystem. The exposure is usually conducted through a mask having apattern corresponding to the desired photoresist pattern. Examples ofthe exposure source include a light source radiating laser light in aUV-region such as a KrF excimer laser (wavelength: 248 nm), an ArFexcimer laser (wavelength: 193 nm) and a F2 laser (wavelength: 157 nm),and a light source radiating harmonic laser light in a far UV region ora vacuum UV region by wavelength conversion of laser light from a solidlaser light source (such as YAG or semiconductor laser). The exposuresource may be electric beam or extremely ultraviolet (EUV).

The step of baking of the exposed composition film is so calledpost-exposure bake, which is conducted with heating means such as hotplates. The temperature of baking of the exposed composition film ispreferably 50 to 200° C., and more preferably 70 to 150° C. Thedeprotection reaction further proceeds by post-exposure bake.

The development of the baked composition film is usually carried outwith a developer using a development apparatus. The development methodincludes dipping methods, paddle methods, spray methods and dynamicdispense method. The developing temperature is preferably 5 to 60° C.,and the developing time is preferably 5 to 300 seconds.

When a positive type photoresist pattern is prepared from thephotoresist composition of the disclosure, the development can beconducted with an alkaline developer. The alkaline developer to be usedmay be any one of various alkaline aqueous solution used in the art.Generally, an aqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. The alkaline developer may comprise asurfactant.

After development, the photoresist film having photoresist pattern ispreferably washed with ultrapure water, and the remained water on thephotoresist film and the substrate is preferably removed therefrom.

When a negative type photoresist pattern is prepared from thephotoresist composition of the disclosure, the development can beconducted with a developer containing an organic solvent, such developeris sometimes referred to as “organic developer”. Examples of an organicsolvent for organic developer include ketone solvents such as2-hexanone, 2-heptanone; glycolether ester solvents such aspropyleneglycolmonomethylether acetate; ester solvents such as butylacetate; glycolether solvents such as propyleneglycolmonomethylether;amide solvents such as N,N-dimethylacetamide; and aromatic hydrocarbonsolvents such as anisole.

The content of organic solvent is preferably from 90% to 100% by weight,more preferably from 95% to 100% by weight, in an organic developer.Preferred is that the organic developer essentially consists of anorganic solvent.

Among them, the organic developer is preferably a developer comprisingbutyl acetate and/or 2-heptanone.

The total content of butyl acetate and 2-heptanone is preferably from50% to 100% by weight, more preferably from 90% to 100% by weight.Preferred is that the organic developer essentially consists of butylacetate and/or 2-heptanone.

The organic developer may comprise a surfactant or a very small amountof water.

Development with an organic developer can be stopped by replacing thedeveloper by other solvent than it such as alcohol.

After development, the photoresist film having a photoresist pattern ispreferably washed with a rinse agent. Such agent is not limited tospecific one provided that it dissolve the film to be washed, example ofwhich include a solvent containing a general organic solvent, preferablyalcohol or ester solvents.

After washing, the remained rinse agent on the photoresist film and thesubstrate is preferably removed therefrom.

The photoresist composition of the disclosure is suitable for KrFexcimer laser lithography, ArF excimer laser lithography, EB (electronbeam) lithography and EUV exposure lithography, particularly for ArFexcimer laser lithography. The photoresist composition is suitable forthe fine processing of the semiconductor.

EXAMPLES

The photoresist composition of the disclosure will be described morespecifically by Examples, which are not construed to limit the scope ofthe disclosure.

The “%” and “part(s)” used to represent the content of any component andthe amount of any material used in the following examples andcomparative examples are on a weight basis unless otherwise specificallynoted.

The weight-average molecular weight of any material used in thefollowing examples is a value found by gel permeation chromatographyunder the following conditions.

Equipment: HLC-8120GPC type, manufactured by TOSOH CORPORATION

Column: Three of TSKgel Multipore HXL-M with guard column, manufacturedby TOSOH CORPORATION

Solvent: tetrahydrofuran,

Flow rate: 1.0 mL/min.

Detector: RI Detector

Column temperature: 40° C.

Injection volume: 100 μL

Standard reference material: standard polystyrene, manufactured by TOSOHCORPORATION.

Synthesis Example 1

To the reactor, 20 parts of the compound represented by formula (I-7-a),200 parts of chloroform and 13 parts of pyridine were added and stirredat 23° C. for 30 minutes. Then to the mixture, 14.13 parts of compoundsrepresented by formula (I-7-b) was fed and stirred at 23° C. for 18hours.

Then, 120 parts of 5% aqueous hydrochloric acid solution were added tothe obtained reaction mixture, and then stirred at 23° C. for 30minutes, followed by standing the mixture still to separate into anorganic layer.

To the organic layer, 60 parts of ion exchanged water was fed and thenstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing process was conducted threetimes.

To the washed organic layer, 0.95 parts of the compound represented byformula (I-7-d) was added, and then refluxed and stirred at 70° C. for10 hours.

Then the reaction mixture was cooled to 23° C., and 60 parts of ionexchanged water was fed and then stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer.

The washing process was conducted five times.

The obtained organic layer was concentrated, followed by separating theobtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 μm, eluent: ethyl acetate] to obtain 7.48 parts ofthe salt represented by the formula (I-7-e).

Into a reactor, 7.29 parts of the compound represented by the formula(I-7-e), 16.77 parts of the compound represented by the formula (I-7-f)and 72.9 parts of 1-chlorobutane, and 0.17 parts of sulfuric acid werecharged, and then refluxed and stirred at 90° C. for 5 hours. Theobtained reaction mixture was cooled into 23° C., 72.9 parts ofn-heptane and 40 parts of ion-exchanged water was added and stirred at23° C. for 30 minutes, followed by standing the mixture still to collectthe washed layer.To collected organic layer, 15 parts of aqueous saturated sodiumbicarbonate solution was added and stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer. Tocollected organic layer, 40 parts of ion-exchanged water was added andstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing step with water was conductedfive times.Then the washed organic layer was concentrated to obtain 11.63 parts ofthe salt represented by the formula (I-7).MS (mass spectrography): 418.1 (molecular ion peak)

Synthesis Example 2

Into a reactor, 7.29 parts of the compound represented by the formula(I-7-e), 10.67 parts of the compound represented by the formula (I-1-f)and 72.9 parts of 1-chlorobutane, and 0.17 parts of sulfuric acid werecharged, and then refluxed and stirred at 90° C. for 10 hours. Theobtained reaction mixture was cooled into 23° C., 72.9 parts ofn-heptane and 40 parts of ion-exchanged water was added and stirred at23° C. for 30 minutes, followed by standing the mixture still to collectthe washed layer.To collected organic layer, 15 parts of aqueous saturated sodiumbicarbonate solution was added and stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer. Tocollected organic layer, 40 parts of ion-exchanged water was added andstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing step with water was conductedfive times.Then the washed organic layer was concentrated, followed by separatingthe obtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 μm, eluent: ethyl acetate] to obtain 1.48 parts ofthe salt represented by the formula (I-1).MS (mass spectrography): 322.1 (molecular ion peak)

Synthesis Example 3

To the reactor, 20 parts of the compound represented by formula (I-7-a),200 parts of chloroform and 13 parts of pyridine were added and stirredat 23° C. for 30 minutes. Then to the mixture, 19.46 parts of compoundsrepresented by formula (I-2-b) was fed and stirred at 23° C. for 18hours.

Then, 120 parts of 5% aqueous hydrochloric acid solution were added tothe obtained reaction mixture, and then stirred at 23° C. for 30minutes, followed by standing the mixture still to separate into anorganic layer.

To the organic layer, 60 parts of ion exchanged water was fed and thenstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing process was conducted threetimes.

To the washed organic layer, 0.95 parts of the compound represented byformula (I-7-d) was added, and then refluxed and stirred at 70° C. for 8hours.

Then the reaction mixture was cooled to 23° C., and 60 parts of ionexchanged water was fed and then stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer.

The washing process was conducted five times.

The obtained organic layer was concentrated, followed by separating theobtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 μm, eluent: ethyl acetate] to obtain 9.22 parts ofthe compound represented by the formula (I-2-e).

Into a reactor, 8.99 parts of the compound represented by the formula(I-2-e), 10.67 parts of the compound represented by the formula (I-1-f)and 75 parts of 1-chlorobutane, and 0.17 parts of sulfuric acid werecharged, and then refluxed and stirred at 90° C. for 18 hours. Theobtained reaction mixture was cooled into 23° C., 75 parts of n-heptaneand 40 parts of ion-exchanged water were added and stirred at 23° C. for30 minutes, followed by standing the mixture still to collect the washedlayer.To collected organic layer, 15 parts of aqueous saturated sodiumbicarbonate solution was added and stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer. Tocollected organic layer, 40 parts of ion-exchanged water was added andstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing step with water was conductedfive times.The obtained organic layer was concentrated, followed by separating theobtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 μm, eluent: ethyl acetate] to obtain 4.24 parts ofthe compound represented by the formula (I-2).MS (mass spectrography): 362.1 (molecular ion peak)

Synthesis Example 4

To the reactor, 20 parts of the compound represented by formula (I-7-a),200 parts of chloroform and 13 parts of pyridine were added and stirredat 23° C. for 30 minutes. Then to the mixture, 26.37 parts of compoundsrepresented by formula (I-3-b) was fed and stirred at 23° C. for 18hours.

Then, 120 parts of 5% aqueous hydrochloric acid solution were added tothe obtained reaction mixture, and then stirred at 23° C. for 30minutes, followed by standing the mixture still to separate into anorganic layer.

To the organic layer, 60 parts of ion exchanged water was fed and thenstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing process was conducted threetimes.

To the washed organic layer, 0.95 parts of the compound represented byformula (I-7-d) was added, and then refluxed and stirred at 70° C. for 8hours.

Then the reaction mixture was cooled to 23° C., and 60 parts of ionexchanged water was fed and then stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer.

The washing process was conducted five times.

The obtained organic layer was concentrated, followed by separating theobtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 μm, eluent: ethyl acetate] to obtain 12.68 parts ofthe compound represented by the formula (I-3-e).

Into a reactor, 11.2 parts of the compound represented by the formula(I-3-e), 10.67 parts of the compound represented by the formula (I-1-f)and 75 parts of 1-chlorobutane, and 0.17 parts of sulfuric acid werecharged, and then refluxed and stirred at 90° C. for 18 hours. Theobtained reaction mixture was cooled into 23° C., 75 parts of n-heptaneand 40 parts of ion-exchanged water were added and stirred at 23° C. for30 minutes, followed by standing the mixture still to collect the washedlayer.To collected organic layer, 15 parts of aqueous saturated sodiumbicarbonate solution was added and stirred at 23° C. for 30 minutes,followed by standing the mixture still to collect the washed layer. Tocollected organic layer, 40 parts of ion-exchanged water was added andstirred at 23° C. for 30 minutes, followed by standing the mixture stillto collect the washed layer. The washing step with water was conductedfive times.

The obtained organic layer was concentrated, followed by separating theobtained concentrates using column [silica gel 60N (spherical shape,neutral), 100 to 210 ∞m, eluent: ethyl acetate] to obtain 6.48 parts ofthe compound represented by the formula (I-3).

MS (mass spectrography): 414.1 (molecular ion peak)

Synthesis Example 5

Into a reactor, 50.49 parts of a salt represented by the formula(B1-5-a) and 252.44 parts of chloroform were charged and stirred at 23°C. for 30 minutes. Then 16.27 parts of a compound represented by theformula (B1-5-b) were dropped thereinto and the obtained mixture wasstirred at 23° C. for one hour to obtain a solution containing a saltrepresented by the formula (B1-5-c).

To the obtained solution, 48.80 parts of a salt represented by theformula (B1-5-d) and 84.15 parts of ion-exchanged water were added andthe obtained mixture was stirred at 23° C. for 12 hours.

From the obtained solution which had two layers, a chloroform layer wascollected and then 84.15 parts of ion-exchanged water were added theretofor washing. These step were conducted five times. To the washedchloroform layer, 3.88 parts of active carbon was added and the obtainedmixture was stirred, followed by filtrating.

The collected filtrate was concentrated and then 125.87 parts ofacetonitrile were added thereto and the obtained mixture was stirred,followed by being concentrated. 20.62 parts of acetonitrile and 309.30parts of tert-butylmethylether were added to the obtained residues,followed by being stirred at 23° C. for about 30 minutes. Then asupernatant was removed therefrom, and the residues were concentrated.To the concentrated residues, 200 parts of n-heptane were added and theobtained mixture was stirred at 23° C. for about 30 minutes, followed bybeing filtrated to obtain 61.54 parts of the salt represented by theformula (B1-5).

MASS (ESI(+) Spectrum): M+375.2

MASS (ESI(−) Spectrum): M−339.1

Synthesis Example 6

The compound represented by the formula (B1-21-b) was produced accordingto a method recited in JP2008-209917A1.

Into a reactor, 30.00 parts of the compound represented by the formula(B1-21-b) and 35.50 parts of a salt represented by the formula(B1-21-a), 100 parts of chloroform and 50 parts of ion-exchanged waterwere charged and stirred at 23° C. for about 15 hours. From the obtainedsolution which had two layers, a chloroform layer was collected and then30 parts of ion-exchanged water was added thereto for washing. Thesesteps were conducted five times.

Then the washed layer was concentrated, and then, 100 parts oftert-butyl methyl ether was added to the obtained residues and theobtained mixture was stirred at 23° C. for about 30 minutes. Theresulting mixture was filtrated to obtain 48.57 parts of the saltrepresented by the formula (B1-21-c).

Into a reactor, 20.00 parts of salt represented by the formula(B1-21-c), 2.84 parts of compound represented by the formula (B1-21-d)and 250 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.21 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for1 hour. The reaction mixture was concentrated, and then, 200 parts ofchloroform and 50 parts of ion-exchanged water were added to theobtained residues and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer. 50 parts ofion-exchanged water was added to the obtained organic layer, and theobtained mixture was stirred at 23° C. for 30 minutes, followed byseparating an organic layer. The washing step with water was conductedfive times. The obtained organic layer was concentrated, and then theobtained residues were dissolved in 53.51 parts of acetonitrile. Thenthe mixture was concentrated, and 113.05 parts of tert-butylmethyletherwas added thereto and the obtained mixture was stirred, followed byfiltrating it to obtain 10.47 parts of the salt represented by theformula (B1-21).

MASS (ESI(+) Spectrum): M+237.1

MASS (ESI(−) Spectrum): M−339.1

Synthesis Example 7

Into a reactor, 11.26 parts of the salt represented by the formula(B1-21-a), 10 parts of the compound represented by the formula(B1-22-b), 50 parts of chloroform and 25 parts of ion-exchanged waterwere charged and stirred at 23° C. for about 15 hours. From the obtainedsolution which had two layers, a chloroform layer was collected and then15 parts of ion-exchanged water were added thereto for washing. Thesesteps were conducted five times.

Then the washed layer was concentrated, and then 50 parts of tert-butylmethyl ether was added to the obtained residues, and the obtainedmixture was stirred at 23° C. for about 30 minutes. The resultingmixture was filtrated to obtain 11.75 parts of the salt represented bythe formula (B1-22-c).

Into a reactor, 11.71 parts of a salt represented by the formula(B1-22-c), 1.70 parts of a compound represented by the formula (B1-21-d)and 46.84 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.12 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for30 minutes. The reaction mixture was concentrated, and then 50 parts ofchloroform and 12.50 parts of ion-exchanged water were added to theobtained residues, and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer. 12.50 parts ofion-exchanged water was added to the obtained organic layer and theobtained mixture was stirred at 23° C. for 30 minutes, followed byseparating an organic layer to wash with water. The washing step withwater was conducted eight times. Then the obtained organic layer wasconcentrated, and 50 parts of tert-butyl methyl ether were added theretoand the obtained mixture was stirred, followed by filtrating it toobtain 6.84 parts of the salt represented by the formula (B1-22).

MASS (ESI(+) Spectrum): M+237.1

MASS (ESI(−) Spectrum): M−323.0

Synthesis of Resin

The monomers used in the syntheses of the resin are as follow.

Hereinafter, these monomers are referred to as “monomer (X)” where “(X)”is the symbol of the formula representing the structure of each monomer.

Synthesis Example 8

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-3) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-3) and monomer (a3-4-2)=45:14:2.5:38.5,and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in propyleneglycolmonomethylether acetate to obtaina solution, and the solution was poured into a mixture of methanol andwater to precipitate the resin. The obtained resin was filtrated. Theseoperations were conducted twice to obtain the copolymer having a weightaverage molecular weight of about 7600 in 68% yield. This resin, whichhad the structural units of the following formulae, was referred to asResin A1-1.

Synthesis Example 9

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-1) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-1) and monomer (a3-4-2)=45:14:2.5:38.5,and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in propyleneglycolmonomethylether acetate to obtaina solution, and the solution was poured into a mixture of methanol andwater to precipitate the resin. The obtained resin was filtrated. Theseoperations were conducted twice to obtain the copolymer having a weightaverage molecular weight of about 7900 in 70% yield. This resin, whichhad the structural units of the following formulae, was referred to asResin A1-2.

Synthesis Example 10

To monomer (I-1), propyleneglycolmonomethylether acetate was added inthe amount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.9% by mole and 2.7% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was poured into methanol to precipitate the resin. Theobtained resin was filtrated to obtain the polymer having a weightaverage molecular weight of about 14000 in 80% yield. This resin, whichhad the structural units of the following formula, was referred to asResin A2-1.

Synthesis Example 11

Monomer (I-1) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-1) and monomer (a5-1-1)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 0.7% by moleand 2.1% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thecopolymer having a weight average molecular weight of about 14000 in 78%yield. This resin, which had the structural units of the followingformulae, was referred to as Resin A2-2.

Synthesis Example 12

Monomer (I-7) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2, 4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.9% by mole and 2.7% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. Thus obtained resin was poured into methanol to precipitatethe resin. The obtained resin was filtrated to obtain the polymer havinga weight average molecular weight of about 15000 in 72% yield. Thisresin, which had the structural units of the following formula, wasreferred to as Resin A2-3.

Synthesis Example 13

Monomer (I-7) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-7) and monomer (a5-1-1)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 0.7% by moleand 2.1% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thecopolymer having a weight average molecular weight of about 16000 in 80%yield. This resin, which had the structural units of the followingformulae, was referred to as Resin A2-4.

Synthesis Example 14

Monomer (I-1) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2, 4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 1.1% by mole and 3.3% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. Thus obtained resin was poured into methanol to precipitatethe resin. The obtained resin was filtrated to obtain the polymer havinga weight average molecular weight of about 8200 in 76% yield. Thisresin, which had the structural units of the following formula, wasreferred to as Resin A2-5.

Synthesis Example 15

Monomer (I-2) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2, 4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 1% by mole and 3% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. Thus obtained resin was poured into methanol to precipitatethe resin. The obtained resin was filtrated to obtain the polymer havinga weight average molecular weight of about 8100 in 78% yield. Thisresin, which had the structural units of the following formula, wasreferred to as Resin A2-6.

Synthesis Example 16

Monomer (I-3) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2, 4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 1% by mole and 3% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. Thus obtained resin was poured into methanol to precipitatethe resin. The obtained resin was filtrated to obtain the polymer havinga weight average molecular weight of about 7900 in 73% yield. Thisresin, which had the structural units of the following formula, wasreferred to as Resin A2-7.

Synthesis Example 17

Monomer (I-3) and monomer (a4-0-12) were mixed together with the moleratio of monomer (I-3) and monomer (a4-0-12)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thecopolymer having a weight average molecular weight of about 8000 in 80%yield. This resin, which had the structural units of the followingformulae, was referred to as Resin A2-8.

Synthesis Example 18

Monomer (I-3), monomer (a4-0-12) and monomer (a5-1-1) were mixedtogether with the mole ratio of monomer (I-3), monomer (a4-0-12) andmonomer (a5-1-1)=50:25:25, and propyleneglycolmonomethylether acetatewas added thereto in the amount equal to 1.5 times by mass of the totalamount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2, 4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 1% by mole and 3% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. Thus obtained resin was poured into methanol to precipitatethe resin. The obtained resin was filtrated to obtain the copolymerhaving a weight average molecular weight of about 7900 in 78% yield.This resin, which had the structural units of the following formulae,was referred to as Resin A2-9.

Synthesis Example 19

Monomer (IX-1) was used, and propyleneglycolmonomethylether acetate wasadded thereto in the amount equal to 1.2 times by mass of the totalamount of monomers to obtain a solution.

Azobis(2,4-dimethylvaleronitrile) was added as an initiator to thesolution in the amount of 3% by mole with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 70°C. Then, the obtained reaction mixture was poured into a large amount ofn-heptane to precipitate a resin. The obtained resin was filtrated toobtain the polymer having a weight average molecular weight of about9900 in 85% yield. This resin, which had the structural units of thefollowing formula, was referred to as Resin A2X-1.

Synthesis Example 20

Monomer (IX-2) and monomer (ax-1) were mixed together with the moleratio of monomer (IX-2) and monomer (ax-1)=30:70, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thecopolymer having a weight average molecular weight of about 9200 in 75%yield. This resin, which had the structural units of the followingformulae, was referred to as Resin A2X-2.

<Preparation of Photoresist Composition>

The following components shown in Table 1 were mixed and dissolved,further, filtrated through a fluorine resin filter having pore diameterof 0.2 μm, to prepare photoresist compositions.

TABLE 1 Resin Acid Quencher (Kind/ generator (Kind/ No. Parts)(Kind/Parts) Parts) PB/PEB Composition 1 A2-1/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-1/10 B1-22/0.4 Composition 2 A2-1/0.4 B1-5/0.4 D1/0.28 90°C./85° C. A1-1/10 B1-22/0.4 Composition 3 A2-2/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-1/10 B1-22/0.4 Composition 4 A2-3/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-1/10 B1-22/0.4 Composition 5 A2-4/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-1/10 B1-22/0.4 Composition 6 A2-1/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-2/10 B1-22/0.4 Composition 7 A2-3/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-2/10 B1-22/0.4 Composition 8 A2-5/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-2/10 B1-22/0.4 Composition 9 A2-6/0.4 B1-21/0.9 D1/0.28 90°C./85° C. A1-2/10 B1-22/0.4 Composition 10 A2-7/0.4 B1-21/0.9 D1/0.2890° C./85° C. A1-2/10 B1-22/0.4 Composition 11 A2-8/0.4 B1-21/0.9D1/0.28 90° C./85° C. A1-2/10 B1-22/0.4 Composition 12 A2-9/0.4B1-21/0.9 D1/0.28 90° C./85° C. A1-2/10 B1-22/0.4 Composition 13A2X-1/0.4 B1-21/0.9 D1/0.28 90° C./85° C. A1-1/10 B1-22/0.4 Composition14 A2X-2/0.4 B1-21/0.9 D1/0.28 90° C./85° C. A1-1/10 B1-22/0.4The symbols shown in Table 1 represent the following components.

<Resin> A1-1: Resin A1-1, A1-2: Resin A1-2, A2-1: Resin A2-1, A2-2:Resin A2-2, A2-3: Resin A2-3, A2-4: Resin A2-4, A2-5: Resin A2-5, A2-6:Resin A2-6, A2-7: Resin A2-7, A2-8: Resin A2-8, A2-9: Resin A2-9, A2X-1:Resin A2X-1, A2X-2: Resin A2X-2 <Acid Generator>

B1-5: Salt represented by formula (B1-5)B1-21: Salt represented by formula (B1-21)B1-22: Salt represented by formula (B1-22)

<Quencher>

D1: Compound as follow, a product of Tokyo Chemical Industry Co., LTD

<Solvent>

Mixture of the following solvents Propyleneglycolmonomethylether acetate265 parts  Propyleneglycolmonomethyl ether 20 parts 2-Heptanone 20 partsγ-butyrolactone 3.5 parts 

(Production of Photoresist Pattern)

Silicon wafers (12 inches) were each coated with “ARC-29”, which is anorganic anti-reflective coating composition available from NissanChemical Industries, Ltd., and then baked at 205° C. for 60 seconds, toform a 78 nm-thick organic anti-reflective coating.

One of the photoresist compositions prepared as above was spin-coatedover the anti-reflective coating so that the thickness of the resultingfilm became 100 nm after drying.

The silicon wafer thus coated with the photoresist composition wasprebaked on a direct hotplate at a temperature shown in the column “PB”in Table 1 for 60 seconds.

Using an ArF excimer stepper for immersion exposure (“XT: 1900Gi”manufactured by ASML, NA=1.35, σ_(out)=0.85, σ_(in)=0.65, XY-pol.illumination) and a mask for preparing trench pattern (pitch: 120 nm,trench width: 40 nm), the wafer thus formed with the composition filmwas subjected to the exposure with the exposure quantity being variedstepwise. Ultrapure water was used for immersion solvent.

After the exposure, the wafer was subjected to post-exposure baking on ahotplate at a temperature shown in the column “PEB” in Table 1 for 60seconds and then to conduct development in the manner of dynamicdispense method for 20 seconds at 23° C. with butyl acetate, product ofTokyo Chemical Industry, Co., Ltd.

Examples 1 to 12 and Comparative Examples 1 and 2

Effective sensibility (ES) means the exposure quantity such that thetrench width of the pattern became 40 nm after exposure through theabove-mentioned mask.

(Line edge roughness (LER) evaluation)

The wall surface of each obtained pattern was observed using a scanningelectron microscope.

The “∘” was given when the pattern has a roughness width of 3 nm orless.

The “x” was given when the pattern has a roughness width of more than 3nm.

Table 2 illustrates the results thereof. The figures in parenthesesrepresent roughness width (nm). Here, the term “roughness width”represents the value (nm) of the maximum difference in the width of thepattern between the convex parts and the concavo parts.

TABLE 2 Ex. No. Composition LER (nm) Ex. 1 Comp. 1 ∘ (2.72) Ex. 2 Comp.2 ∘ (2.78) Ex. 3 Comp. 3 ∘ (2.74) Ex. 4 Comp. 4 ∘ (2.73) Ex. 5 Comp. 5 ∘(2.76) Ex. 6 Comp. 6 ∘ (2.68) Ex. 7 Comp. 7 ∘ (2.70) Ex. 8 Comp. 8 ∘(2.66) Ex. 9 Comp. 9 ∘ (2.65) Ex. 20 Comp. 10 ∘ (2.62) Ex. 12 Comp. 11 ∘(2.65) Ex. 12 Comp. 12 ∘ (2.60) Comparative Compar. Comp. 1 x (3.22) Ex.1 Comparative Compar. Comp. 2 x (3.68) Ex. 2The photoresist compositions of the disclosure can provide photoresistpattern with decreased line edge roughness.The photoresist composition is useful for fine processing ofsemiconductors.

What is claimed is:
 1. A photoresist composition comprising: a resin(A1) which has an acid-labile group; a resin (A2) which comprises astructural unit represented by formula (I);

wherein R¹ represents a C1-C13 fluorinated saturated hydrocarbon group,A¹ represents a single bond, a C1-C6 alkanediyl group, or*-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-, where * represents a binding site to anoxygen atom, A², A³ and A⁴ each independently represent a C₁ to C₆alkanediyl group, X¹ and X² each independently represent —O—, —CO—O— or—O—CO—, a represents 0 or 1 and b represents 0 or 1, and R² represents aC1-C18 hydrocarbon group; and an acid generator.
 2. The photoresistcomposition according to claim 1, wherein the resin (A2) comprises thestructural unit represented by formula (I) in an amount of 50% to 100%by mole of all the structural units of the resin (A2).
 3. Thephotoresist composition according to claim 1, wherein the resin (A2)consists of the structural unit represented by formula (I).
 4. Thephotoresist composition according to claim 1, further comprising a saltwhich generates an acid weaker in acidity than an acid generated fromthe acid generator.
 5. A process for producing a photoresist patterncomprising the following steps (1) to (5): (1) a step of applying thephotoresist composition according to claim 1 on a substrate, (2) a stepof forming a composition film by drying the composition, (3) a step ofexposing the composition film to radiation, (4) a step of baking theexposed composition film, and (5) a step of developing the bakedcomposition film, thereby forming the photoresist pattern.